| 摘要 |
PURPOSE:To prepare an intermediate for the selective synthesis of a natural fermentation type thienamycin, in high yield, by converting the OH or OH and NH2 of an easily preparable specific amino ester compound used as starting material to trialkyl silyl groups, subjecting the compound to ring-closing reaction, and eliminating the trialkylsilyl groups. CONSTITUTION:A compound of formula VI (R1 and R2 are alkyl) is used as a raw material, and reacted with trialkyl halogenosilane to convert the OH or the OH and the NH2 groups to trialkylsilyl groups. The product is subjected to ring-closing by Gringnard reaction to obtain the compound of formula IX. Elimination of the trialkylsilyl groups gives the thienamycin intermediate of formula II. The compound of formula VI can be prepared by (1) reacting the simple compound of formula III with the compound of formula IV to afford a novel isoxazoline of formula V, and (2) reducing the compound with sodium borohydride, etc. in the presence of nickel chloride, etc. The reduction after the silylation affords the ring-closing reaction keeping the original steric configuration in high yield and low isomer production. |
