Synthesis of new chiral <i>N</i>-arylsulfonyl-1,3-oxazolidin-2-ones from α-amino acids

Ahmed Ould Aliyenne; Jamil Kraïem; Yakdhane Kacem; Béchir Ben Hassine

doi:10.1016/j.crci.2006.10.004

Synthesis of new chiral N-arylsulfonyl-1,3-oxazolidin-2-ones from α-amino acids

Ahmed Ould Aliyenne ¹; Jamil Kraïem ¹; Yakdhane Kacem ¹; Béchir Ben Hassine ¹

¹ Laboratoire de synthèse organique asymétrique et catalyse homogène, faculté des sciences de monastir, avenue de l'Environnement, 5019 Monastir, Tunisia

Comptes Rendus. Chimie, Catalyse asymétrique, Volume 10 (2007) no. 3, pp. 251-258.

Abstracts

English
French

A variety of new chiral N-arylsulfonyl-1,3-oxazolidin-2-ones were prepared in three steps starting from (d)- and (l)-amino acid. N-Arylsulfonyl amino alcohols, derived from amino acids, were carbonylated with the bis-(trichloromethyl) carbonate (BTC), in the presence of triethylamine, to provide optically pure N-phenylsulfonyloxazolidin-2-ones 3a–f, N-naphthylsulfonyloxazolidin-2-ones 3g–j and N-tosylsulfonyloxazolidin-2-ones 3k–p in good yields.

Re´sume´

Une variété de nouvelles N-arylsulfonyloxazolidin-2-ones chirales a été préparée en trois étapes à partir d'acides α-aminés (d) et (l). Les N-arylsulfonyl aminoalcools, dérivés des acides aminés, ont été carbonylés par l'intermédiaire du carbonate de bis-trichlorométhyle, avec de bons rendements chimiques.

Metadata

Received: 2006-04-12
Accepted: 2006-10-20
Published online: 2006-12-20

DOI: 10.1016/j.crci.2006.10.004

Keywords: Amino acids, Bis-(trichloromethyl)carbonate, N-Arylsulfonyloxazolidin-2-ones, Acides aminés, Carbonate de bis-trichlorométhyle, N-Arylsulfonyloxazolidin-2-ones

Author's affiliations:

Ahmed Ould Aliyenne ¹; Jamil Kraïem ¹; Yakdhane Kacem ¹; Béchir Ben Hassine ¹

¹ Laboratoire de synthèse organique asymétrique et catalyse homogène, faculté des sciences de monastir, avenue de l'Environnement, 5019 Monastir, Tunisia

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     author = {Ahmed Ould Aliyenne and Jamil Kra{\"\i}em and Yakdhane Kacem and B\'echir Ben Hassine},
     title = {Synthesis of new chiral {\protect\emph{N}-arylsulfonyl-1,3-oxazolidin-2-ones} from \ensuremath{\alpha}-amino acids},
     journal = {Comptes Rendus. Chimie},
     pages = {251--258},
     publisher = {Elsevier},
     volume = {10},
     number = {3},
     year = {2007},
     doi = {10.1016/j.crci.2006.10.004},
     language = {en},
}

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Ahmed Ould Aliyenne; Jamil Kraïem; Yakdhane Kacem; Béchir Ben Hassine. Synthesis of new chiral N-arylsulfonyl-1,3-oxazolidin-2-ones from α-amino acids. Comptes Rendus. Chimie, Catalyse asymétrique, Volume 10 (2007) no. 3, pp. 251-258. doi : 10.1016/j.crci.2006.10.004. https://comptes-rendus.academie-sciences.fr/chimie/articles/10.1016/j.crci.2006.10.004/

Original version of the full text

The full text below may contain a few conversion errors compared to the version of record of the published article.

1 Introduction

1,3-Oxazolidin-2-ones are structural components of many compounds that display pharmacological properties [1–11]. Furthermore, they have also been used as chiral auxiliaries and intermediates in asymmetric synthesis of numerous pharmaceutical products [12,13].

During the past few years, significant progress has been made in the discovery of new biologically active N-aryl and N-alkyloxazolidin-2-ones [14–16]. However, the N-sulfonylated oxazolidin-2-ones were not sufficiently elaborated, and only few reports have described the synthesis of N-tosyloxazolidin-2-ones [17–19].

Several methods have been employed for the synthesis of racemic and optically active oxazolidin-2-ones. One of the most efficient methods to build the heterocyclic carbamate involves the condensation of 1,2-amino alcohols with carbonyl derivatives such as phosgene [20], trichloromethyl chloroformate [18], bis-(trichloromethyl) carbonate [21], isocyanates [12], chloroformates [22], ureas [23], or diethylcarbonate [24]. The catalyzed addition of CO₂ to aziridines has also been employed to prepare racemic N-tosyloxazolidin-2-ones [17].

Izuhara et al. [18] have described a four-step synthesis of the optically pure 4-benzyl-3-tosyloxazolidin-2-one starting from (l)-phenylalanine. In this sequence, the trichloromethyl chloroformate has been employed as a carbonylating agent. In this work, we describe a three-step synthesis of a variety of new chiral N-arylsulfonyloxazolidin-2-ones, using the same strategy cited above. We have employed the bis-(trichloromethyl) carbonate (BTC) instead of the trichloromethyl chloroformate, since it appears to be safer due to its lower vapor pressure and higher stability [25].

2 Results and discussion

Enantiomerically pure N-arylsulfonyloxazolidin-2-ones are prepared in three steps from commercially available (d)- and (l)-amino acid. As illustrated in Scheme 1, sulfonylation of α-amino acids with arylsulfonylchlorides, in a two-phase mixture of i-PrNEt₂ in acetone and aqueous NaOH, leads to the N-arylsulfonyl amino acids 1a–p, which were then reduced to the N-arylsulfonyl amino alcohols 2a–p with good to excellent yields (Table 1) by use of lithium aluminium hydride in THF or (THF:Et₂O). The same procedure has been employed by Berry and Craig [26] to prepare N-tosyl-α-amino alcohols from α-amino acids. These authors have determined the enantiomeric purity of N-tosyl-α-amino alcohols (entry 2m–p) by the formation of the corresponding MTPA esters [27], the minor diastereoisomers have not been detected in the 500 MHz ¹H NMR spectrum of the crude product [26].

Scheme 1
Synthesis of N-arylsulfonyl-α-amino alcohols.

Entry	R	Ar	Config.	[α]_D	m.p. (°C)	Yields (%)
2a	i-Pr	C₆H₅–	S	−10	76–78	98
2b	Me	C₆H₅–	S	+15	Oil	97
2c	i-Bu	C₆H₅–	S	+18	102–104	99
2d	Ph	C₆H₅–	R	−10	114–116	98
2e	Bn	C₆H₅–	S	+18.7	64–66	95
2f	s-Bu	C₆H₅–	S	+25	58–60	99
2g	Me	2-Naphthyl	S	+23	82–84	82
2h	i-Pr	2-Naphthyl	S	−10	96–98	86
2i	s-Bu	2-Naphthyl	S	+18	112–114	85
2j	Bn	2-Naphthyl	S	+22	106–108	75
2k	s-Bu	p-H₃C–C₆H₄–	S	−15	80–81	98
2l	Ph	p-H₃C–C₆H₄–	R	−10	93–94	97
2m	i-Pr	p-H₃C–C₆H₄–	S	+16.8	88–89	98 (99)^a
2n	i-Bu	p-H₃C–C₆H₄–	S	+23.7	105–106	96 (98)^a
2o	Bn	p-H₃C–C₆H₄–	S	−15	74–75	97 (99)^a
2p	Me	p-H₃C–C₆H₄–	S	+15.8	57–58	98 (100)^a

^a Chemical yields 2m–p reported by Berry and Craig [26].

As far as we know, compounds 2a–l were prepared for the first time during this study. Compounds 2m–p were prepared by Barry and Craig [26].

Subsequent reaction of compounds 2a–p with BTC, in the presence of Et₃N at −78 °C to r.t., provided the corresponding N-arylsulfonyloxazolidin-2-ones 3a–p in excellent yields without racemization, as confirmed by chiral HPLC analysis on tow compounds (entries 3c and 3h) (Scheme 2).

Scheme 2
Synthesis of N-arylsulfonyloxazolidin-2-ones.

In Table 2, are given the chemical yields and the physical properties of compounds 3a–p, which have not been reported to date, except compound 3p.

Entry	R	Ar	Config.	m.p. (°C)	[α]_D	Yields (%)
3a	Bn	C₆H₅−	S	107–109	+38.3	96
3b	i-Pr	C₆H₅–	S	99–101	+56.8	95
3c	Me	C₆H₅–	S	60–62	+45.0	95
3d	i-Bu	C₆H₅–	S	139–141	+39.6	96
3e	Ph	C₆H₅–	R	118–120	−13.6	97
3f	s-Bu	C₆H₅–	S	144–146	+60.0	95
3g	Me	2-Naphthyl	S	129–131	+40.1	88
3h	i-Pr	2-Naphthyl	S	141–143	+16.7	85
3i	s-Bu	2-Naphthyl	S	130–132	+60.0	81
3j	Bn	2-Naphthyl	S	126–128	+71.4	79
3k	i-Pr	p-H₃C–C₆H₄–	S	115–118	+58.2	95
3l	i-Bu	p-H₃C–C₆H₄–	S	151–153	+38.4	96
3m	s-Bu	p-H₃C–C₆H₄–	S	170–172	+41.0	95
3n	Me	p-H₃C–C₆H₄–	S	117–119	+52.2	97
3o	Ph	p-H₃C–C₆H₄–	R	149–151	−39.5	95
3p	Bn	p-H₃C–C₆H₄–	S	136–138	+36.2	96

3 Conclusion

We have synthesized, in good yields, a variety of new chiral N-arylsulfonyloxazolidin-2-ones from their corresponding α-amino acids. The test of the biological activity and the study of synthetic properties of these new products are under investigation in our laboratory.

4 Experimental section

TLC was performed on Merck 60F-254 silica gel plates (layer thickness 0.25 mm). Column chromatography was performed on silica gel (70–230 mesh) using ethylacetate and cyclohexane mixture as eluents. Melting points were determined on a Electrothermal 9002 apparatus and are uncorrected. ¹H NMR spectra were recorded at 300 MHz. All chemical shifts are reported as δ values (ppm) relative to internal tetramethylsilane. CH₂Cl₂, THF were respectively distilled over CaH₂ and Na/benzophenone. Elemental analyses were carried out by ‘Service de microanalyse’ of ‘Institut national de recherche et d'analyse physico-chimique de Tunis’. HPLC analyses were conducted on a methanol/hexane [70:30] system with a UV detector at 254 nm, using a Chirobiotic V column (250 × 46 mm) and a flow rate of 0.6 mL/min.

N-Arylsulfonyl amino alcohols 2a–p were prepared according to literature [26]; compounds 2m–p were reported by Berry and Craig [26].

4.1 (2S)-N-(Phenylsulfonyl)valinol: 2a

Yield = 98%; m.p.: 76–78 °C [hexane:ethylacetate (90:10)]. IR (cm⁻¹): ν_NH = 3215, ν_OH = 3493; [α]_D = −10 (c = 1, CHCl₃). ¹H NMR (300 MHz, CDCl₃): 0.70–0.79 (2d, 6H); 1.73–1.82 (m, 1H); 2.22 (s, 1H); 3.03–3.09 (m, 1H); 3.54–361 (m, 2H); 5.24 (d, 1H); 7.28–7.60 (m, 3H); 7.92 (d, 1H). ¹³C NMR (75 MHz, CDCl₃): (18.80, 19.49, 2CH₃–); (29.83, –CH–); (61.48, CH–NH–); (63.41, –CH₂–O–); (127.49–140.93, C_arom). Anal. calc. for C₁₁H₁₇NO₃S (243.32): C, 54.30; H, 7.04; N, 5.76. Found: C, 54.20; H, 7.20; N, 5.72.

4.2 (2S)-N-(Phenylsulfonyl)alaninol: 2b

Yield = 97%; oil; [α]_D = +15 (c = 0.6, CHCl₃). IR (cm⁻¹): ν_NH = 3217, ν_OH = 3477. ¹H NMR (300 MHz, CDCl₃): 0.98 (d, 3H); 3.01–3.06 (m, 1H); 3.08 (s, 1H); 3.37–3.58 (m, 3H); 5.75 (s, 1H); 7.48–7.60 (m, 3H); 7.91 (d, 2H). ¹³C NMR (75 MHz, CDCl₃): (17.28, 1CH₃–); (51.91, –CH–NH–); (66.47, –CH₂–O–); (127.35 and 141.01, C_arom). Anal. calc. for C₉H₁₃NO₃S (215.27): C, 50.22; H, 6.09; N, 6.51. Found: C, 50.10; H, 6.10; N, 6.42.

4.3 (2S)-N-(Phenylsulfonyl)leucinol: 2c

Yield = 99%; m.p.: 102–104 °C [hexane:ethylacetate (90:10)]; [α]_D = +18 (c = 1, CHCl₃). IR (cm⁻¹): ν_NH = 3201, ν_OH = 3397. ¹H NMR (300 MHz, CDCl₃): 0.61–0.68 (2d, 6H); 1.22–1.51 (m, 2H); 3.02 (s, 1H); 3.17–3.56 (m, 3H); 5.25 (d, 1H); 7.30–7.53 (m, 3H); 7.86 (d, 2H). ¹³C NMR (75 MHz, CDCl₃): (20.24, 22.30, 2CH₃–); (38.75, –CH₂–); (51.72, CH–NH–); (64.92, –CH₂–O–); (126.48–140.25, C_arom). Anal. calc. for C₁₂H₁₉NO₃S (257.35): C, 56.01; H, 7.44; N, 5.44. Found: C, 55.80; H, 7.42; N, 5.39.

4.4 (2S)-N-(Phenylsulfonyl)phenylglycinol: 2d

Yield = 98%; m.p.: 114–116 °C [hexane:ethylacetate (90:10)]; [α]_D = −10 (c = 0.5, CHCl₃). IR (cm⁻¹): ν_NH = 3302, ν_OH = 3477. ¹H NMR (300 MHz, CDCl₃): 3.35 (s, 1H); 3.72–3.75 (m, 2H); 4.07–4.59 (m, 1H); 6.25 (d, 1H); 7.04–7.37 (m, 10H). ¹³C NMR (75 MHz, CDCl₃): (60.23, CH–NH–); (66.49, –CH₂–O–); (126.76–140.56, C_arom). Anal. calc. for C₁₄H₁₅NO₃S (277.34): C, 60.63; H, 5.45; N, 5.05. Found: C, 60.53; H, 5.42; N, 5.10.

4.5 (2S)-N-(Phenylsulfonyl)phenylalaninol: 2e

Yield = 95%; m.p.: 64–66 °C [hexane:ethylacetate (90:10)]; [α]_D = +18.7 (c = 0.5, CHCl₃). IR (cm⁻¹): ν_NH = 3193, ν_OH = 3416. ¹H NMR (300 MHz, CDCl₃): 2.64–2.83 (dd, 2H); 3.46–3.70 (m, 3H); 5.40 (d, 1H); 6.90–7.73 (m, 10H). ¹³C NMR (75 MHz, CDCl₃): (38.10, –CH₂–); (57.22, –CH–NH–); (64.36, –CH₂–O–); (126.76–140.30, C_arom). Anal. calc. for C₁₅H₁₇NO₃S (291.36): C, 61.83; H, 5.88; N, 4.81. Found: C, 61.72; H, 5.80; N, 5.80.

4.6 (2S, 3S)-N-(Phenylsulfonyl)isoleucinol: 2f

Yield = 99%; m.p.: 58–60 °C [hexane:ethylacetate (90:10)]; [α]_D = +25 (c = 0.6, CHCl₃). IR (cm⁻¹): ν_NH = 3216, ν_OH = 3408. ¹H NMR (300 MHz, CDCl₃): 0.69 (d, 3H); 0.86 (t, 3H); 1.02 (m, 2H); 1.41–1.52 (m, 2H); 2.35 (s, 1H); 3.15–3.24 (m, 1H); 3.52–3.54 (m, 2H); 5.09 (d, 1H); 7.23–7.51 (m, 3H); 7.86 (d, 2H). ¹³C NMR (75 MHz, CDCl₃): (13.24, 22.91, 2CH₃–); (25.39, 35.27, 2-CH–); (60, CH–NH–); (60.65, –CH₂–O–); (127.34–142.58, C_arom). Anal. calc. for C₁₂H₁₉NO₃S (257.35): C, 56.01; H, 7.44; N, 5.44. Found: C, 56.10; H, 7.52; N, 5.42.

4.7 (2S)-N-(2-Naphthylsulfonyl)alaninol: 2g

Yield = 82%; m.p.: 82–84 °C [hexane:ethylacetate (90:10)]; [α]_D = +23 (c = 1, CHCl₃). IR (cm⁻¹): ν_NH = 3175, ν_OH = 3327. ¹H NMR (300 MHz, DMSO): 1.81 (d, 3H); 2.21 (s, 1H); 3.72–4.64 (m, 3H); 5.64 (s, 1H); 7.58–7.81 (m, 2H); 7.90–8.18 (m, 4H); 8.69 (s, 1H). ¹³C NMR (75 MHz, DMSO): (20.11, CH₃–); (56.86, CH–NH–); (70.89, –CH₂–O–); (119.73–13251, C_arom).

4.8 (2S)-N-(2-Naphthylsulfonyl)valinol: 2h

Yield = 85%; m.p.: 96–98 °C [hexane:ethylacetate (90:10)]; [α]_D = −10 (c = 1, CHCl₃). IR (cm⁻¹): ν_NH = 3187, ν_OH = 3491. ¹H NMR (300 MHz, DMSO): 0.61–0.89 (2d, 6H); 2.05 (s, 1H); 3.89–4.51 (m, 3H); 5.82 (d, 1H); 7.60–7.73 (m, 2H); 7.89–8.05 (m, 4H); 8.54 (s, 1H). ¹³C NMR (75 MHz, DMSO): (16.27, 20.07, 2CH₃–); (30.10, –CH–); (61.20, CH–NH–); (66.92, –CH₂–O–); (120.12–1139.75, C_arom). Anal. calc. for C₁₅H₁₉NO₃S (293.38): C, 61.41; H, 6.53; N, 4.77. Found: C, 60.80; H, 7.10; N, 4.62.

4.9 (2S, 3S)-N-(2-Naphthylsulfonyl)isoleucinol: 2i

Yield = 86%; m.p.: 112–114 °C [hexane:ethylacetate (90:10)]; [α]_D = +18 (c = 1, CHCl₃). IR (cm⁻¹): ν_NH = 3217, ν_OH = 3512. ¹H NMR (300 MHz, DMSO): 0.81 (d, 3H); 0.83–0.99 (t, 3H); 1.24–1.42 (m, 2H); 1.57–2.74 (m, 1H); 2.18 (s, 1H); 3.86–4.29 (m, 3H); 5.71 (d, 1H); 7.18–7.41 (m, 2H); 7.68–8.27 (m, 4H); 8.83 (s, 1H). ¹³C NMR (75 MHz, DMSO): (1125, 13.08, 2CH₃–); (26.24, –CH–) (36.18, –CH₂–); (60.64, CH–NH–); (66.71, –CH₂–O–); (122.08–139.16, C_arom).

4.10 (2S)-N-(2-Naphthylsulfonyl)phenylalaninol: 2j

Yield = 75%; m.p.: 106–108 °C [hexane:ethylacetate (90:10)]; [α]_D = +22 (c = 1, CHCl₃). IR (cm⁻¹): ν_NH = 3211, ν_OH = 3519. ¹H NMR (300 MHz, DMSO): 2.09 (s, 1H); 2.82–2.89 (m, 1H); 3.41–3.48 (m, 1H); 3.98–4.12 (m, 2H); 4.57–4.62 (m, 1H); 5.75 (d, 1H); 7.21–7.45 (m, 5H); 7.62–7.74 (m, 2H); 8.01–8.16 (m, 4H); 8.74 (s, 1H). ¹³C NMR (75 MHz, DMSO): (40.21, –CH₂–); (57.51, CH–N–); (67.95, –CH₂–O–); (121.75–136.93, C_arom).

4.11 (2S)-N-(4-Methylbenzenesulfonyl)isoleucinol: 2k

Yield = 98%; m.p.: 80–81 °C [hexane:ethylacetate (90:10)]; [α]_D = −15 (c = 1, CHCl₃). IR (cm⁻¹): ν_NH = 3300, ν_OH = 3481. ¹H NMR (300 MHz, CDCl₃): 0.75 (d, 3H); (t, 3H); 0.91 (m, 2H); 1.35–1.49 (m, 2H); 2.2 (s, 1H); 2.42 (s, 3H); 3.09–3.13 (m, 1H); 3.55–3.56 (m, 2H); 5.1 (d, 1H); 7.28–7.79 (AA′BB′, 4H). ¹³C NMR (75 MHz, CDCl₃): (11.72–21.91, 3CH₃–); (25.60, 36.75, 2-CH–); (60.11 and 60.78, CH–NH–, –CH₂–O–); (127.12–143.50, C_arom). MS: C₁₃H₂₁NSO₃; MW = 271 g/mol; m/z = 240 (C₁₁H₁₈NSO₃⁺, 51%); m/z = 155 (C₇H₇SO₂⁺, 67%); m/z = 91 (C₇H₇⁺, 100%).

4.12 (2S)-N-(4-Methylbenzenesulfonyl)phenylglycinol: 2l

Yield = 97%; m.p.: 93–94 °C [hexane:ethylacetate (90:10)]; [α]_D = −10 (c = 1, CHCl₃). IR (cm⁻¹): ν_NH = 3319, ν_OH = 3396. ¹H NMR (300 MHz, CDCl₃): 2.4 (s, 3H); 2.68–2.76 (dd, 2H); 3.49–3.65 (m, 3H); 5.15 (d, 1H); 6.95–7.58 (m, 9H). ¹³C NMR (75 MHz, CDCl₃): (21.61, CH₃–); (61.24, CH–NH–); (67.08, –CH₂–O–); (126.67–141.27, C_arom). MS: C₁₃H₂₁NSO₃; MW = 305 g/mol; m/z = 274 (C₁₄H₁₆NSO₃⁺, 8%); m/z = 214 (C₇H₉NSO₃⁺, 38%); m/z = 155 (C₇H₇SO₂⁺, 50%); m/z = 91 (C₇H₇⁺, 100%).

4.13 Preparation of (4S)-3-(phenylsulfonyl)-4-benzyloxazolidin-2-one: 3a

To a solution of bis-(trichloromethyl)carbonate (0.43 g, 1.44 mmol, 0.3 eq) in CH₂Cl₂ (20 mL) at −78 °C was slowly added a solution of N-(phenylsulfonyl)phenylalaninol 2e (1.07 g, 3.68 mmol) in CH₂Cl₂ (40 mL). After 15 min of stirring, triethylamine (10 mmol, 1.4 mL, 3 eq) in CH₂Cl₂ (80 mL) was added dropwise maintaining the temperature below −70 °C. The resulting mixture was stirred at −78 °C for 5 min and then the ethylacetate–N₂ (liquid) bath was removed. The reaction mixture was stirred at room temperature for 2 h and washed with 1 N HCl (50 mL) and brine (3 × 25). Evaporation of the solvent under reduced pressure gave a residue, which was purified by chromatography on silica gel using [cyclohexane/ethylacetate (8:2)], as mobile phase.

Yield = 96%; m.p.: 107–109 °C [hexane:ethylacetate (90:10)]; [α]_D = +38.3 (c = 1, CHCl₃). IR (cm⁻¹): ν_CO = 1772. ¹H NMR (300 MHz, CDCl₃): 2.83–2.88 (m, 1H); 3.49–3.55 (m, 1H); 4.11–4.20 (m, 2H); 4.65–4.73 (m, 1H); 7.02–7.70 (m, 10H). ¹³C NMR (75 MHz, CDCl₃): (40.13, –CH₂–); (58.41, CH–N–); (67.06, –CH₂–O–); (127.99–138.48, C_arom); (152.38, CO). MS: C₁₆H₁₅NO₄S; MW = 317 g/mol; m/z = 253 (C₁₆H₁₅NO₂⁺, 64%); m/z = 141 (C₆H₅O₂S⁺, 81%); m/z = 91 (C₇H₇⁺, 100%); m/z = 77 (C₆H₅⁺, 43%). Anal. calc. for C₁₆H₁₅NO₄S (317.36): C, 60.55; H, 4.76; N, 4.41. Found: C, 60.10; H, 4.32; N, 4.20.

4.14 (4S)-3-(Phenylsulfonyl)-4-i-propyloxazolidin-2-one: 3b

Compound 3b (90:10); [α]_D = +58.8 (c = 0.5, CHCl₃). IR (cm⁻¹): ν_CO = 1761. ¹H NMR (300 MHz, CDCl₃): 0.70–0.94 (2d, 6H); 2.41–2.52 (m, 1H); 4.14–4.48 (m, 3H); 7.54–8.11 (m, 5H). ¹³C NMR (75 MHz, CDCl₃): (14.30, 18.16, 30.24, 3CH₃–); (62.08, CH–NH–); (63.90, –CH₂–O–); (128.74–138.46, C_arom); (152.79, CO). MS: C₁₂H₁₅NO₄S; MW = 269 g/mol; m/z = 226 (C₉H₈NO₄S⁺, 38%); m/z = 205 (C₁₂H₁₅NO₂⁺, 12%); m/z = 176 (C₉H₈NO₂⁺, 31%); m/z = 141 (C₇H₇SO₂⁺, 100%); m/z = 77 (C₆H₅⁺, 67%). Anal. calc. for C₁₂H₁₅NO₄S (269.32): C, 53.52; H, 5.61; N, 5.20. Found: C, 53.40; H, 5.52; N, 5.13.

4.15 (4S)-3-(Phenylsulfonyl)-4-methyloxazolidin-2-one: 3c

Yield = 95%; m.p.: 60–62 °C [hexane:ethylacetate (90:10)]; [α]_D = +45 (c = 1, CHCl₃). IR (cm⁻¹): ν_CO = 1761. ¹H NMR (300 MHz, CDCl₃): 1.48 (d, 3H); 3.87–3.91 (m, 1H); 4.37–4.56 (m, 2H); 7.50–8.03 (m, 5H). ¹³C NMR (75 MHz, CDCl₃): (20.66, CH₃–); (53.71, CH–NH–); (69.70, –CH₂–O–); (128.31–138.05, C_arom); (152.17, CO). MS: C₁₀H₁₁NO₄S; MW = 241 g/mol; m/z = 241 M⁺, 7%); m/z = 226 (C₉H₈NO₄S⁺, 30%); m/z = 177 (C₁₀H₁₁NO₂⁺, 55%); m/z = 141 (C₆H₅SO₂⁺, 100%); m/z = 77 (C₆H₅⁺, 57%). Anal. calc. for C₁₀H₁₁NO₄S (241.26): C, 49.78; H, 4.60; N, 5.81. Found: C, 49.72; H, 4.53; N, 5.60.

Enantiomeric purity of 3c was determined by HPLC analyses on Chirobiotic V column (250 × 46 mm) with a flow rate of 0.6 mL/min. Mobile phase methanol/hexane [70:30]; retention times: (4S)-3-(phenylsulfonyl)-4-methyloxazolidin-2-one 10.4 min; (4R)-3-(phenylsulfonyl)-4-methyloxazolidin-2-one 15.2 min.

4.16 (4S)-3-(Phenylsulfonyl)-4-i-butyloxazolidin-2-one: 3d

Yield = 96%; m.p.: 139–141 °C [hexane:ethylacetate (90:10)]; [α]_D = +39.6 (c = 0.5, CHCl₃). IR (cm⁻¹): ν_CO = 1770. ¹H NMR (300 MHz, CDCl₃): 0.90–1.05 (m, 6H); 1.56–1.67 (m, 2H); 1.94–2.04 (m, 1H); 4.05–4.09 (m, 1H); 4.36–452 (m, 2H); 7.54–8.08 (m, 5H). ¹³C NMR (75 MHz, CDCl₃): (21.44, 23.61, 24.67, 3CH₃–); (42.87, –CH₂–); (56.27, CH–NH–); (68.15, –CH₂–O–); (128.41–138.21, C_arom); (152, CO). MS: C₁₃H₁₇NO₄S; MW = 283 g/mol; m/z = 219 (C₁₃H₁₇NO₂⁺, 13%); m/z = 162 (C₉H₈NO₂⁺, 24%); m/z = 141 (C₆H₅SO₂⁺, 100%); m/z = 77 (C₆H₅⁺, 67%). Anal. calc. for C₁₃H₁₇NO₄S (283.34): C, 55.11; H, 6.05; N, 494. Found: C, 55.01; H, 6.17; N, 4.83.

4.17 (4R)-3-(Phenylsulfonyl)-4-phenyloxazolidin-2-one: 3e

Yield = 97%; m.p.: 118–120 °C [hexane:ethylacetate (90:10)]; [α]_D = −13.6 (c = 1, CHCl₃). IR (cm⁻¹): ν_CO = 1775. ¹H NMR (300 MHz, CDCl₃): 4.27–4.31 (m, 1H); 4.71–4.77 (t, 1H); 5.42–5.46 (m, 1H); 7.19–7.55 (m, 10H). ¹³C NMR (75 MHz, CDCl₃): (60.41, CH–NH–); (70.51, –CH₂–O–); (127.12–137.68, C_arom); (152.02, CO). MS: C₁₅H₁₃NO₄S; MW = 303 g/mol; m/z = 239 (C₁₅H₁₃O₂N⁺, 65%); m/z = 141 (C₆H₅O₂S⁺, 100%); m/z = 77 (C₆H₅⁺, 58%). Anal. calc. for C₁₅H₁₃NO₄S (303.33): C, 59.40; H, 4.32; N, 4.62. Found: C, 59.20; H, 4.21; N, 4.65.

4.18 (4S)-3-(Phenylsulfonyl)-4-[(1′S)-1′-methylpropyl]oxazolidin-2-one: 3f

Yield = 95%; m.p.: 144–146 °C [hexane:ethylacetate (90:10)]; [α]_D = 60 (c = 1, CHCl₃). IR (cm⁻¹): ν_CO = 1772. ¹H NMR (300 MHz, CDCl₃): 0.72 (d, 3H); 0.96–1.00 (t, 3H); 1.09–1.34 (m, 2H); 2.22 (m, 1H); 4.12–4.16 (m, 1H); 4.25–4.31 (t, 1H); 4.53–4.56 (m, 1H); 7.55–8.11 (m, 5H). ¹³C NMR (75 MHz, CDCl₃): (11.68, 12.19, 2CH₃–); (25.65, –CH–); (37.05, –CH₂–); (61.05, CH–NH–); (63.94, –CH₂–O–); (128.76–138.40, C_arom); (152.87, CO). MS: C₁₃H₁₇NO₄S; MW = 283 g/mol; m/z = 219 (C₁₃H₁₇NO₂⁺, 17%); m/z = 226 (C₉H₈NO₄S⁺, 15%); m/z = 141 (C₆H₅SO₂⁺, 100%); m/z = 77 (C₆H₅⁺, 63%). Anal. calc. for C₁₃H₁₇NO₄S (283.34): C, 55.11; H, 6.05; N, 4.94. Found: C, 55.10; H, 5.76; N, 4.80.

4.19 (4S)-3-(2-Naphthylsulfonyl)-4-methyloxazolidin-2-one: 3g

Yield = 88%; m.p.: 129–131 °C [hexane:ethylacetate (90:10)]; [α]_D = +40.1 (c = 0.5, CHCl₃). IR (cm⁻¹): ν_CO = 1762. ¹H NMR (300 MHz, CDCl₃): 1.59 (d, 3H); 3.93–4.66 (m, 3H); 7.62–7.73 (m, 2H); 7.92–8.05 (m, 4H); 8.68 (s, 1H). ¹³C NMR (75 MHz, CDCl₃): (21.19, CH₃–); (54.04, CH–NH–); (69.96, –CH₂–O–); (122.94–135.94, C_arom); (152.47, CO). MS: C₁₄H₁₃NO₄S; MW = 291 g/mol; m/z = 291 (M⁺, 13%); m/z = 227 (C₁₄H₁₃NO₂⁺, 35%); m/z = 168 (C₁₂H₁₀N⁺, 26%); m/z = 127 (C₁₀H₇⁺, 100%). Anal. calc. for C₁₄H₁₃NO₄S (291.32): C, 57.72; H, 4.50; N, 4.81. Found: C, 57.62; H, 4.41; N, 4.62.

4.20 (4S)-3-(2-Naphthylsulfonyl)-4-i-propyloxazolidin-2-one: 3h

Yield = 85%; m.p.: 141–143 °C [hexane:ethylacetate (90:10)]; [α]_D = +16.7 (c = 0.5, CHCl₃). IR (cm⁻¹): ν_CO = 1766. ¹H NMR (300 MHz, CDCl₃): 0.74–0.97 (2d, 6H); 4.14–4.53 (m, 3H); 7.61–7.72 (m, 2H); 7.91–8.02 (m, 4H); 8.68 (s, 1H). ¹³C NMR (75 MHz, CDCl₃): (14.39, 18.17, 2CH₃–); (30.13, –CH–); (62.14, CH–NH–); (63.94, –CH₂–O–); (122.57–135.91, C_arom); (152.87, CO). MS: C₁₇H₁₉NO₄S; MW = 333 g/mol; m/z = 319 (M⁺, 11%); m/z = 212 (C₁₃H₁₀NO₂⁺, 31%); m/z = 191 (C₁₀H₇NO₂S⁺, 52%); m/z = 127 (C₁₀H₇⁺, 100%). Anal. calc. for C₁₆H₁₇NO₄S (319.38): C, 60.17; H, 5.37; N, 4.39. Found: C, 59.95; H, 5.11; N, 4.44.

Enantiomeric purity of 3c was determined by HPLC analyses on Chirobiotic V column (250 × 46 mm) with a flow rate of 0.6 mL/min. Mobile phase methanol/hexane [70:30]; retention times: (4S)-3-(2-naphthylsulfonyl)-4-i-propyloxazolidin-2-one 11.2 min; (4R)-3-(2-naphthylsulfonyl)-4-i-propyloxazolidin-2-one 13.3 min.

4.21 (4S)-3-(2-Naphthylsulfonyl)-4-[(1′S)-1′-methylpropyl]oxazolidin-2-one: 3i

Yield = 87%; m.p.: 130–132 °C [hexane:ethylacetate (90:10)]; [α]_D = +60 (c = 1, CHCl₃). IR (cm⁻¹): ν_CO = 1776. ¹H NMR (300 MHz, CDCl₃): 0.74 (d, 3H); 0.98–1.02 (t, 3H); 1.16–1.37 (m, 2H); 2.04–2.17 (m, 1H); 4.13–4.61 (m, 3H); 7.12–7.15 (m, 2H); 7.62–8.05 (m, 4H); 8.69 (s, 1H). ¹³C NMR (75 MHz, CDCl₃): (11.75, 12.11, 2CH₃–); (25.68, –CH–); (37.20, –CH₂–); (61.11, CH–NH–); (63.94, –CH₂–O–); (122.93–135.91, C_arom); (152.93, CO). MS: C₁₇H₁₉NO₄S; MW = 333 g/mol; m/z = 333 (M⁺, 7%); m/z = 212 (C₁₃H₁₀NO₂⁺, 23%); m/z = 191 (C₁₀H₇NO₂S⁺, 64%); m/z = 127 (C₁₀H₇⁺, 100%). Anal. calc. for C₁₇H₁₉NO₄S (333.40): C, 61.24; H, 5.74; N, 4.20. Found: C, 61.20; H, 5.72; N, 4.10.

4.22 (4S)-3-(2-Naphthylsulfonyl)-4-benzyloxazolidin-2-one: 3j

Yield = 79%; m.p.: 107–109 °C [hexane:ethylacetate (90:10)]; [α]_D = +71.4 (c = 0.5, CHCl₃). IR (cm⁻¹): ν_CO = 1773. ¹H NMR (300 MHz, CDCl₃): 2.84–2.93 (m, 1H); 3.57–3.63 (m, 1H); 4.10–4.27 (m, 2H); 4.71–4.80 (m, 1H); 7.15–7.39 (m, 5H); 7.64–7.75 (m, 2H); 7.95–8.11 (m, 4H); 8.74 (s, 1H). ¹³C NMR (75 MHz, CDCl₃): (40.26, –CH₂–); (58.49, CH–N–); (67.05, –CH₂–O–); (122.95–135.99, C_arom); (152.42, CO). MS: C₁₇H₁₉NO₄S; MW = 367 g/mol; m/z = 212 (C₁₃H₁₀NO₂⁺, 15%); m/z = 191 (C₁₀H₇NO₂S⁺, 72%); m/z = 127 (C₁₀H₇⁺, 100%); m/z = 91 (C₇H₇⁺, 100%). Anal. calc. for C₂₀H₁₇NO₄S (367.42): C, 65.38; H, 4.66; N, 3.81. Found: C, 65.32; H, 4.62; N, 3.82.

4.23 (4S)-3-(4-Methylbenzenesulfonyl)-4-i-propyloxazolidin-2-one: 3k

Yield = 95%; m.p.: 115–117 °C [hexane:ethylacetate (90:10)]; [α]_D = +58.2 (c = 0.5, CHCl₃). IR (cm⁻¹): ν_CO = 1770. ¹H NMR (300 MHz, CDCl₃): 0.72–0.92 (2d, 6H); 2.43 (s, 3H); 4.12–4.45 (m, 3H); 7.32–7.96 (AA′BB′, 4H). ¹³C NMR (75 MHz, CDCl₃): (14.3–22, 3CH₃–); (30.26, –CH–); (62.05, CH–NH–); (63.91, –CH₂–O–); (128.7–147.9, C_arom); (152.8, CO). MS: C₁₃H₁₇NSO₄; MW = 283 g/mol; m/z = 240 (C₁₀H₁₀NSO₄⁺, 13%); m/z = 219 (C₁₃H₁₇NO₂⁺, 13%); m/z = 176 (C₁₀H₁₀NO₂⁺, 33%); m/z = 155 (C₇H₇SO₂⁺, 100%); m/z = 91 (C₇H₇⁺, 88%). Anal. calc. for C₁₃H₁₇NO₄S (283.34): C, 55.11; H, 6.05; N, 4.94. Found: C, 55.40; H, 5.80; N, 4.70.

4.24 (4S)-3-(4-Methylbenzenesulfonyl)-4-i-butyloxazolidin-2-one: 3l

Yield = 96%; m.p.: 151–153 °C [hexane:ethylacetate (90:10)]; [α]_D = +38.4 (c = 0.5 CHCl₃). IR (cm⁻¹): ν_CO = 1768. ¹H NMR (300 MHz, CDCl₃): 0.95–0.98 (m, 6H); 1.58–1.64 (m, 2H); 1.97 (m, 1H); 2.43 (s, 3H); 4.03–4.45 (m, 3H); 7.33–7.95 (AA′BB′, 4H). ¹³C NMR (75 MHz, CDCl₃): (21.7–25.06, 3CH₃–); (43.19, –CH₂–); (56.59, CH–NH–); (68.48, –CH₂–O–); (128.81–145.94, C_arom); (152.66, CO). MS: C₁₄H₁₉NSO₄; MW = 297 g/mol; m/z = 233 (C₁₄H₁₉NO₂⁺, 7%); m/z = 176 (C₁₀H₁₀NO₂⁺, 15%); m/z = 155 (C₇H₇SO₂⁺, 100%); m/z = 91 (C₇H₇⁺, 71%). Anal. calc. for C₁₄H₁₉NO₄S (297.37): C, 56.55; H, 6.44; N, 4.71. Found: C, 55.30; H, 6.32; N, 4.60.

4.25 (4S)-3-(4-Methylbenzenesulfonyl)-4-[(1′S)-1′-methylpropyl]oxazolidin-2-one: 3m

Yield = 95%; m.p.: 170–172 °C [hexane:ethylacetate (90:10)]; [α]_D = +41 (c = 1, CHCl₃). IR (cm⁻¹): ν_CO = 1774. ¹H NMR (300 MHz, CDCl₃): 0.72 (d, 3H); 0.96 (t, 2H); 2.43 (s, 3H); 4.09–4.54 (m, 3H); 7.32–7.96 (AA′BB′, 4H). ¹³C NMR (75 MHz, CDCl₃): (11.54, 11.90, 2CH₃–); (25.51, –CH–) (36.89, –CH₂–); (61.31, CH–NH–); (63.82, –CH₂–O–); (127.32–138.41, C_arom); (152.75, CO). MS: C₁₄H₁₉NSO₄; MW = 297 g/mol; m/z = 233 (C₁₄H₁₉NO₂⁺, 10%); m/z = 240 (C₁₀H₁₀NSO₄⁺, 18%); m/z = 155 (C₇H₇SO₂⁺, 100%); m/z = 91 (C₇H₇⁺, 58%). Anal. calc. for C₁₄H₁₉NO₄S (297.37): C, 56.55; H, 6.44; N, 4.71. Found: C, 56.50; H, 6.42; N, 4.62.

4.26 (4S)-3-(4-Methylbenzenesulfonyl)-4-methyloxazolidin-2-one: 3n

Yield = 97%; m.p.: 117–119 °C [hexane:ethylacetate (90:10)]; [α]_D = +52.2 (c = 0.5, CHCl₃). IR (cm⁻¹): ν_CO = 1779. ¹H NMR (300 MHz, CDCl₃): 1.52 (d, 3H); 2.4 (s, 3H); 3.89–4.57 (m, 3H); 5.15 (d, 1H); 7.33–7.95 (AA′BB′, 4H). ¹³C NMR (75 MHz, CDCl₃): (21–22, 2CH₃–); (53.96, CH–NH–); (69.92, –CH₂–O–); (128.71–150.95, C_arom); (152.50, CO). MS: C₁₁H₁₃NSO₄; MW = 255 g/mol; m/z = 255 (M⁺, 4%); m/z = 254 (C₁₁H₁₂NSO₄⁺, 32%); m/z = 191 (C₁₁H₁₃NO₂⁺, 50%); m/z = 91 (C₇H₇⁺, 73%); m/z = 64 (SO₂⁺, 74%). Anal. calc. for C₁₁H₁₃NO₄S (255.29): C, 51.75; H, 5.13; N, 5.49. Found: C, 51.70; H, 5.20; N, 5.40.

4.27 (4R)-3-(4-Methylbenzenesulfonyl)-4-phenyloxazolidin-2-one: 3o

Yield = 95%; m.p.:149–151 °C [hexane:ethylacetate (90:10)]; [α]_D = −39.5 (c = 0.5, CHCl₃). IR (cm⁻¹): ν_CO = 1774. ¹H NMR (300 MHz, CDCl₃): 2.37 (d, 3H); 4.25–4.29 (m, 1H); 5.41–5.43 (m, 1H); 7.09–7.31 (m, 9H). ¹³C NMR (75 MHz, CDCl₃): (22.01, 1CH₃–); (60.75, CH–NH–); (70.87, –CH₂–O–); (127.41–145.59, C_arom); (152.45, CO). MS: C₁₆H₁₅NSO₄; MW = 317 g/mol; m/z = 253 (C₁₆H₁₅NO₂⁺, 71%); m/z = 91 (C₇H₇⁺, 100%); m/z = 77 (C₆H₅⁺, 55%). Anal. calc. for C₁₆H₁₅NO₄S (317.36): C, 60.55; H, 4.76; N, 4.41. Found: C, 60.52; H, 4.72; N, 4.25.

4.28 (4S)-3-(4-Methylbenzenesulfonyl)-4-benzyloxazolidin-2-one: 3p

Yield = 96%; m.p.: 136–138 °C [hexane:ethylacetate (90:10)]; [α]_D = +36.2 (c = 0.5, CHCl₃). IR (cm⁻¹): ν_CO = 1774. ¹H NMR (300 MHz, CDCl₃): 2.37 (d, 3H); 4.25–4.29 (m, 1H); 5.41–5.43 (m, 1H); 7.09–7.31 (m, 9H). ¹³C NMR (75 MHz, CDCl₃): (22, 1CH₃–); (41.25, –CH₂–); (60.7, CH–NH–); (70.8, –CH₂–O–); (127.40–145.59, C_arom); (152.45, CO). MS: C₁₆H₁₅NO₄S; MW = 317 g/mol; m/z = 253 (C₁₆H₁₅NO₂⁺, 71%); m/z = 155 (C₇H₇SO₂⁺, 10%); m/z = 91 (C₇H₇⁺, 100%); m/z = 77 (C₆H₅⁺, 55%). Anal. calc. for C₁₇H₁₇NO₄S (331.39): C, 61.62; H, 5.17; N, 4.23. Found: C, 61.50; H, 5.20; N, 4.20.

Acknowledgments

We are grateful to the DGRSRT (the Direction générale de la Recherche scientifique et de la Rénovation technologique) for grants to ‘Laboratoire de synthèse organique asymétrique et catalyse homogène’.

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[26] B.M. Berry; D. Craig Synlett (1992), p. 41

[27] J.A. Dale; D.L. Dull; H.S. Mosher J. Org. Chem., 34 (1969), p. 2543

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