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Note | Special issue | Vol 52, No. 1, 2000, pp.451-457
Published online, 1st January, 1970
DOI: 10.3987/COM-99-S7
Reactions of Cage-annulated 2-Methyl-5-(trifluoromethanesulfonyloxy)furans with Lithium Diisopropylamide. Evidence for Nucleophilic Reactivity of LDA

Alan P. Marchand* and Irishi Narayanan Narayanan Namboothiri

*Department of Chemistry, University of North Texas, Texas 76203, U.S.A.

Abstract

Reaction of 3-trifluoromethanesulfonyloxy-5-methyl-4-oxahexacyclo-[5.4.1.02,6.03,10.05,9.08,11]dodecane (6a) with lithium diisopropylamide (LDA, 6 equivalents) in dry THF affords 11-methylenepentacyclo[5.4.0.02,6.03,10.05,9]undecan-8-one (3a) in low yield (11%). This reaction is shown to proceed via formation of an intermediate cage-annulated hemiaminal (7a), which in turn may have resulted via a highly unusual nucleophilic attack by (i-Pr)2N:- upon exo-11-diisopropylamino-endo-11-methylpentacyclo[5.4.0.02,6.03,10.05,9]undecan-8-one (8a). The corresponding reaction of 3-trifluoromethanesulfonyloxy-5,9,10-trimethyl-4-oxahexacyclo[5.4. 1.02,6.03,10.05,9.08,11]dodecane (6b) with LDA (6 equivalents) in dry THF produced 1,7-dimethyl-11-methylenepentacyclo[5.4.0.02,6.03,10.05,9]undecan-8-one (3b) in 10% isolated yield.