| 摘要 |
Novel bile acids according to the general formula (I) wherein R1 represents a hydroxyl group, R2 and R3 both represent a hydrogen or a hyroxyl group, or R2 represents a hydroxyl group or a .beta. hydroxyl groupand R3 represents a hydrogen or R3 represents a hydroxyl group and R2 represents a hydrogen, and R4 represents a -COOH group or (CH2)nR5 wherein n is from 1 to 6, and R5 represents -COOH, -(COOH)2, -O-PO(OH)2, -CH(OH)COOH, a nitrogen containing saturated heterocyclic ring group, NR_ 6R7, wherein R6 and R7 are the same or different and each represent hydrogen or a C1-C10 alkyl group or CO-R8 wherein R8 represents an amino acid moiety, R-phenylglycine, 12-aminododecanoic acid or 4-aminohippuric acid are synthesized from cholic, deoxycholic, chenodeoxycholic, ursodeoxycholic and lithocholic acids and iodo-derivatives thereof by known processes and/or by novel processes according to the present invention. The novel processes of the present invention are (1) a free radical Michael-type chain lengthening approach and using a free radical mediator such as new tris(trimethylsilyl)silane (TTMSS); and (2) a malonate ester chain lengthening approach. The bile acids with systematic modifications in their structures can play an important role in understanding their mechanistic actions in biology and chemistry.
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