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Photochemistry of δ‐hydroxybutyl α,β‐unsaturated γ,δ‐epoxy nitriles. Formation of spiro ketals
Author(s) -
Ishii Keitaro,
Kotera Masashi,
Nakano Takao,
Zenko Tatsuya,
Sakamoto Masanori,
Iida Ikuo,
Nishio Takehiko
Publication year - 1994
Publication title -
liebigs annalen
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 0947-3440
DOI - 10.1002/jlac.199519950106
Subject(s) - chemistry , ylide , solvent , epoxide , double bond , sigmatropic reaction , ether , epoxy , medicinal chemistry , organic chemistry , catalysis
Photocyclization reactions of δ‐hydroxybutyl α,β‐unsaturated γ,δ‐epoxy nitriles 4a, b at 254 nm lead to spiro ketals 5a, b and 6a, b arising from the carbonyl ylide intermediate A . The spiro ketal 6b containing an endocyclic double bond is transformed to spiro ether 16 by an acid‐catalyzed 1,3‐sigmatropic rearrangement. The ratio of spiro ketals 5 and 6 has been shown to depend on solvent polarity and acidity of additives. Application to the synthesis of pheromones is presented. X‐ray crystal structure analyses are performed on dispiro compound 18 and spiro ester 25 .