Regioselectivity of the Intermolecular Diels-Alder Reaction of Acyl Nitroso Compounds (C-Nitrosocarbonyl Compounds) and Nitrosoformates (O-Nitrosocarbonyl Compounds). Preparation of Functionalized cis-Δ6-1-Octalones

Article abstract of DOI:10.1021/jo00211a025

A study of the regioselectivity of the intermolecular Diels-Alder reaction of (nitrosocarbonyl)benzene and methyl nitrosoformate with representative electron-rich and electron-deficient 2-substituted 1,3-cyclohexadienes is described.The observed results are consistent with the prediction that nitrosocarbonyl compounds behave as dependable electron-deficient 2? components in a normal (HOMO_diene controlled) Diels-Alder reaction with electron-rich 2-substituted dienes and additionally illustrate that they may serve as useful 2? components in regioselective Diels-Alder reactions with electron-deficient 2-substituted 1,3-cyclohexadienes.The latter results are consistent with either a normal (HOMO_diene controlled) or inverse electron demand (LUMO_diene controlled) Diels-Alder reaction.Utilization of the nitrosocarbonyl Diels-Alder adducts in a stereospecific preparation of functionalized, cis-Δ⁶-1-octalone is detailed.In contrast to predictions based on secondary orbital control (allylic axial heteroatom orbital control), <4 + 2> cycloaddition of butadiene with the 5- and 6-substituted N-benzoyl 3-aza-2-oxobicyclo<2.2.2>oct-5-enes occurs on the face bearing the RCON-O bridge.