1-Oxa-2,3-cyclohexadiene (I) can be readily generated by treatment of 5-bromo-3,4-dihydro-2H-pyran with potassium tert-butoxide in the presence of 18-crown-6 and can be trapped with dienes or olefins. Thus, the treatment of I with furan gave 50% yield of Diels-Alder adduct II, whereas with 1,1-diphenylethylene I gave 43% of the [2+2]cycloadduct III. The remarkable regio- and stereoselectivities with which [4+2] and [2+2] adducts are formed suggests a concerted, non-radical cycloaddn. mechanism. [on SciFinder (R)]
Title
1-Oxa-2,3-cyclohexadiene (\"2H-isopyran\"): a strained heterocyclic allene undergoing cycloaddition reactions with characteristic typo-, regio- and stereoselectivities
Published in
Tetrahedron
Volume
47
Issue
26
Pages
4603-10
Date
1991
ISSN
0040-4020
Note
CAN 115:114311
27-13
Heterocyclic Compounds (One Hetero Atom)
Dip. Chim.,Univ. Perugia,Perugia,Italy.
Journal
written in English.
110-00-9 (Furan) Role: RCT (Reactant), RACT (Reactant or reagent) (Diels-Alder reaction of, with oxacyclohexadiene); 41527-51-9 (2-(2-Tetrahydropyranyloxy)cyclobutanone) Role: RCT (Reactant), RACT (Reactant or reagent) (Wittig reaction of, with ethyltriphenylphosphonium bromide); 1530-32-1 (Ethyltriphenylphosphonium bromide) Role: RCT (Reactant), RACT (Reactant or reagent) (Wittig reaction of, with tetrahydropyranyloxycyclobutanone); 110-87-2 Role: RCT (Reactant), RACT (Reactant or reagent) (bromination of); 513-81-5 (2,3-Dimethyl-1,3-butadiene); 530-48-3 (1,1-Diphenylethylene); 590-18-1 (cis-2-Butene); 624-64-6 (trans-2-Butene); 873-66-5 (trans-1-Phenyl-1-propene) Role: PROC (Process) (cycloaddn. of, with oxacyclohexadiene); 26274-19-1 Role: RCT (Reactant), RACT (Reactant or reagent) (cycloaddn. reactions of oxacyclodiene generated from); 121055-33-2P (Oxacyclohexa-2,3-diene) Role: PREP (Preparation) (generation and cycloaddn. of, with alkenes); 135735-37-4P; 135735-38-5P; 135735-39-6P; 135735-41-0P; 135819-98-6P; 135819-99-7P Role: PRP (Properties), SPN (Synthetic preparation), PREP (Preparation) (prepn. and NMR of); 135735-40-9P Role: RCT (Reactant), SPN (Synthetic preparation), PREP (Preparation), RACT (Reactant or reagent) (prepn. and O-methylation of); 121029-59-2P; 121029-61-6P; 121029-62-7P; 135735-42-1P; 135735-43-2P Role: SPN (Synthetic preparation), PREP (Preparation) (prepn. of)
Record creation date
2006-03-03
