Studies on the synthesis of bafilomycin A1: Stereochemical aspects of the fragment assembly aldol reaction for construction of the C(13)-C(25) segment

William R. Roush*, Thomas D. Bannister, Michael D. Wendt, Jill A. Jablonowski, Karl A. Scheidt

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

52 Scopus citations

Abstract

Highly stereoselective syntheses of aldols 8a-c corresponding to the C(13)-C(25) segment of bafilomycin A1 were developed by routes involving fragment assembly aldol reactions of chiral aldehyde 6a and the chiral methyl ketones 7. A remote chelation effect plays a critical role in determining the stereoselectivity of the key aldol coupling of 6a and the lithium enolate of 7b. The protecting group for C(23)-OH of the chiral aldehyde fragment also influences the selectivity of the lithium enolate aldol reaction. In contrast, the aldol reaction of 6a and the chlorotitanium enolates of 7a,c were much less sensitive to the nature of the C(15)-hydroxyl protecting group. Studies of the reactions of chiral aldehydes with Takai's (y-methoxyallyl)chromium reagent 40 are also described. The stereoselectivity of these reactions is also highly dependent on the protecting groups and stereochemistry of the chiral aldehyde substrates.

Original languageEnglish (US)
Pages (from-to)4275-4283
Number of pages9
JournalJournal of Organic Chemistry
Volume67
Issue number12
DOIs
StatePublished - Jun 14 2002

ASJC Scopus subject areas

  • Organic Chemistry

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