Stereoselectivity in the Ene reaction of syn- and anti-1-(4-tert-butylcyclohexylidene)-4-tert-butylcyclohexane with singlet oxygen, nitrosyl hydride, nitrosoformaldehyde, 4-phenyl-1,2,4-triazol-3,5-dione, diethyl azodicarboxylate and methyl propiolate

Abstract

The stereochemistries of the ene reactions of synand anti-1 -(4-tertbutylcyclohexylidene) -4-tertbutylcyclohexane (I and II) with a series of enophiles X=Y (singlet oxygen, nitrosyl hydride, nitroso-

Inductive and Resonance Effects of Substituents on π-Face Selection

“…A number of ene and oxidation reactions of methylenecyclohexanes, including 1 O 2 addition, OsO 4 dihydroxylation, and perimidic acid or dioxirane epoxidations, occur faster on the equatorial π-face. − This preference is puzzling in light of the propensity for the axial attack on methylenecyclohexanes displayed, e.g., by peracids, , halonium ions, and [2+2]-cycloaddition reagents . The available examples of ene additions, epoxidations, and related electrocyclic additions to methylenecyclohexanes are listed in Scheme . − The set of listed reactions seems too diverse to map out a reaction coordinate for additions to the exocyclic double bond. However, if it does, the axial preference reaches two maxima along that path, i.e., variation in the sensitivity of electrophiles to stereoelectronic control of additions to methylenecyclohexane resembles the corresponding variation among nucleophiles and could perhaps be related to reactivity.…”

Generation and Trapping of Nitrosocarbonyl Intermediates

“…The reaction smoothly proceeds at room temperature in DMF as solvent in the presence of an excess of 9,10-dimethylanthracene (9,10-DMA) in a typical HDA cycloaddition reaction, affording the N -formylnitroso derivative up to 79% yields (Scheme ). Cycloadduct 6 is submitted to further treatment with Me 2 NH in alcoholic solution to prepare the deformylated compound 7 . Both these cycloadducts are characterized by a thermal lability (vide infra) and were used in a cycloreversion reaction to generate respectively the nitrosoformaldehyde (HCONO) 1a and the nitrosyl hydride (HNO).…”