作者:Tsung-Chin Tseng、Ming-Jing Wu
DOI:10.1016/0957-4166(95)00208-7
日期:1995.7
The conjugate addition of thioacetic acid (3 equivalents) to (4S)-4-phenyl-N-methacryloyloxazolidin-2-one (3) in the presence of TiCl4 (1.5 equivalents) gave the addition adducts in 87% yield and only 14% de. When this reaction was carried out in the absence of TiCl4, good diastereoselectivity (94% de) was observed. A similar result was obtained by employing thiobenzoic acid as a nucleophile. The reaction of 3 with other thiols, such as thiophenol, 4-methoxythiophenol, 2-methoxytbiophenol, methyl 3-mercatopropionate, methyl thioglycolate and methyl thiosalicylate, required TiCl4 (1.5 equivalents) to give the addition adducts in good chemical yields and the diastereoselectivities are ranging from 50 to 82% de. 2-Aminothiophenol was also employed in this study to give the addition adducts in 60% yield and 70% de when the reaction was carried out in the absence of TiCl4. In the presence of TiCl4, this reaction provided the addition adducts as racemic mixture in 28% yield along with 1,5-benzothiazepin-4-one 10 in 56% yield.