PHOTOCHEMISTRY OF 1-ACETOXY-2-(PENT-4-ENOYL) CYCLOPENTENES : AN EFFICIENT SYNTHESIS OF 7-ACETOXY-5-METHYLTRICYCLO [5. 3. 0] DECAN-2-ONE, A POTENTIAL INTERMEDIATE TO PSEUDOGUAIANE RING

概要

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The intramolecular photocycloadditions of 1-acetoxy-2-(pent-4-enoyl) cyclopentene (3a) and its analogues have been investigated. The 4'-methyl analogue (3b) afforded a straight adduct (4b) in 82.5% yield as a sole product, in contrast to the case for (3a) resulting in a mixture of the straight and cross adducts, (4a) and (5a), in a 1 : 1-1 : 8 ratio. On the other hand, 5', 5'-dimethyl analogue (3c) yielded the cross adduct (5c) together with a major product (6) due to a concurrent photo-ene reaction. The differences of regioselectivity due to the substitution pattern of the terminal double bond in (3) may be interpreted in terms of the preferential formation of corresponding exciplexes governed by non-bonding steric interactions.
公益社団法人日本薬学会の論文
1984-09-25