Enantiodivergent Synthesis of Both Enantiomers of Marine Alkaloids Haliclorensin and Isohaliclorensin, a Constituent of Halitulin
摘要:
Starting from (3R)-5-benzotriazolyl-3-phenylperhydropyrido[2,1-b][1,3]oxazole 9, the enantiodivergent syntheses of both enantiomers of the marine alkaloids haliclorensin 1 and isohaliclorensin 3 have been achieved. Our syntheses feature ring-expansion reactions for the formation of the aza-macrocycle ring system of 3 and sequential ring-expansion reactions (aza-Claisen rearrangement and Zip reaction) for the formation of the aza-macrocycle ring system of 1.
LiNH2BH3-promoted reductive opening of 8-substituted phenylglycinol-derived oxazolopiperidone lactams leads to enantiopure 4-substituted-5-aminopentanols, which are used as starting building blocks in the synthesis of the Haliclona alkaloids haliclorensin C, haliclorensin, and halitulin (formal). The starting lactams are easily accessible by a cyclocondensation reaction of (R)-phenylglycinol with racemic γ-subtituted
Revision of the structure of haliclorensin to (S)-7-methyl-1,5-diazacyclotetradecane and confirmation of the new structure by synthesis
作者:Markus R Heinrich、Yoel Kashman、Peter Spiteller、Wolfgang Steglich
DOI:10.1016/s0040-4020(01)01020-1
日期:2001.12
A reinvestigation of the marine alkaloid haliclorensin led to a revision of the proposed structure to 7-methyl-1,5-diazacyclotetradecane. The new structure was confirmed by total synthesis of both optical forms. According to chiroptical measurements and GC–MS investigations, natural haliclorensin consists of a 3:1 mixture of the (S)- and (R)-enantiomers.