The assignment of cis and trans configurations in N‐protected 4‐substituted 2‐tributylstannyl‐1,3‐oxazolidines by NMR has been achieved through the use of extrapolations of Karplus−Kitching‐type relationships for 3J(119Sn−C−Z−13C) to establish the shape of the oxazolidine ring. Examination of 3J(H,H) allowed the determination of torsion angles for the substituents on C4 and C5, discrimination being completed by comparison of the H2 chemical shifts, together with the 2J(Sn−C−H2) values. The validity of the method was subsequently corroborated by comparison of the results obtained for the liquid phase with those obtained from radiocrystallographic structures of triphenylstannyl analogues or DFT calculations on trimethylstannyl analogues. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)

N‐Protected 2‐tributylstannyl‐1,3‐oxazolidines derived from N‐monoprotected chiral β‐amino alcohols were obtained through transacetalisation of (diethoxymethyl)tributylstannane under acidic conditions. In the case of 4‐substituted 2‐tributylstannyl‐1,3‐oxazolidines, the kinetic product of the reaction was shown to be the trans isomer whatever the nature of the protective group, while the thermodynamic product was the cis isomer in the N‐Ts series and the trans isomer in N‐CO2R compounds. Aspects of the transacetalisation reaction are discussed along with those concerning the isomerisation of the products, allowing an interpretation of the obtained results. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)

Precursors of Chiral α-Amino Anions: An Improved Synthesis of Chiral N-(α-Tributylstannylorgano)oxazolidin-2-ones Derived from (R)-or (S)-Phenylglycinol. -Efficient reaction conditions are reported for the cyclization of phenylglycinol carbamates of type (I) to chiral oxazolidinones. -(COEFFARD, V.; LE GROGNEC*, E.; BEAUDET, I.; LEPELTIER, M.; LEAT-CREST, V.; QUINTARD,

A convenient and versatile method for the synthesis of N-(a-tributylstannylorgano)oxazolidin-2-ones under mild experimental conditions is described. Treatment of various N-(a-tributylstannylorgano)phenylglycinol carbamates with sodium hydride in DMF or with mesyl chloride/triethylamine in dichloromethane at room temperature affords the functionalized N-(a-tributylstannylorgano)oxazolidin-2-ones in yields up to 90%. Their subsequent transmetalation reaction, leading to chiral a-amino anions, is briefly discussed.