中文名称 | 英文名称 | CAS号 | 化学式 | 分子量 |
---|---|---|---|---|
(2S,4s)-3-苯甲酰基-2-叔丁基-4-甲基-1,3-噁唑啉-5-酮 | (2S,4S)-3-benzoyl-2-(tert-butyl)-4-methyl-1,3-oxazolidin-5-one | 104057-64-9 | C15H19NO3 | 261.321 |
—— | 3-Benzoyl-2-(tert-butyl)-4-methyl-1,3-oxazolidin-5-one | —— | C15H19NO3 | 261.321 |
—— | (2S,4S)-3-benzoyl-2-t-butyl-4-<(methylsulfonyl)methyl>oxazolidin-5-one | 147092-24-8 | C16H21NO5S | 339.412 |
中文名称 | 英文名称 | CAS号 | 化学式 | 分子量 |
---|---|---|---|---|
—— | (2S,4R)-3-benzoyl-2-tert-butyl-4-[(1',3'-dioxan-2'-yl)methyl]oxazolidin-5-one | —— | C18H23NO5 | 333.384 |
The cyclopropanation reactions of (1a) with ethyl and t-butyl (dimethylsulfuranylidene)acetate proceeded with good diastereoselectivity and resulted in the formation of three diastereoisomeric products. The major diastereoisomeric product ((2a) and (2b), respectively) could be isolated in pure form by simple recrystallization. The stereochemistry of the major cyclopropane product (2b) has been determined by single-crystal X-ray structural analysis. These cyclopropanation products were susceptible to ring opening of the cyclopropane ring upon reduction with sodium borohydride or acid hydrolysis. The reaction of (1b) with ethyl (dimethylsulfuranylidene)acetate gave a mixture of four diastereoisomeric cyclopropanation products. The reactions of (1a) and (1b) with the sulfur ylide derived from 3-methoxycarbonylallyldimethylsulfonium bromide were less successful in terms of product diastereoselectivities.
The 1,3-dipolar cycloaddition reactions of (1) and (11) with the azomethine ylides derived from N-benzylidene α-amino acid esters (2) proceed with good to high exo-diastereoselectivity giving the cycloadducts (4) and (12), respectively. The cycloaddition adducts can be converted to highly functionalised prolines (14), (15) and (17) in high enantiomeric purities. The Michael addition adducts of (1) and (11) with the azomethine ylides derived from the N-(disubstituted methylidene) α-amino acid esters (18), (19) and (33) allow for a practical synthesis of all four stereoisomers of 4-benzamidopyroglutamate. The stereochemistry of these cycloaddition and Michael adducts has been extensively determined by single-crystal X-ray structural analysis [compounds (4b), (5b,d), (12b,d), (13e), (15), (20), (21) and (27)]. Lithium-chelated transition state structures have been proposed to rationalize the stereochemical outcomes of these reactions.