Bernard Miller

Reactions of 2-phenylcyclohexanone derivatives. A re-examination

Abstract The product commonly obtained from bromination of 2-phenylcyclohexanone is cis -2-bromo-6-phenylcyclohexanone, formerly considered to be 2-bromo-2-phenylcyclohexanone. The initial bromination product, however, is trans -2-bromo-6-phenylcyclohexanone. The two stereoisomers are readily interconverted in acid, and the cis -isomer is normally obtained due to its lower solubility in several solvents. Dehydrobromination of the cis or trans bromoketones gives a mixture of 2-phenylcyclohex-2-en-1-one and 6-phenylcyclohex-2-en-1-one, which do not interconvert under the reaction conditions. Alkylation and cyanoethylation of 2-phenylcyclohex-2-en-1-one proceed normally at C-2.

Stereochemistry and mechanisms of thermal cycloaddition reactions of conjugated enynes. The stereospecific formation of six tetrahedral centers in a single reaction

Abstract Thermal condensations of penta-1,5-dien-3-ynes with two molecules of olefinic dienophiles proceed stereospecifically with retention of the configurations of the dienophiles, and with both molecules of the dienophile in each reaction adding to the same face of the dienyne.

An addition—cyclization—elimination mechanism for dehydro Diels-Alder reactions

Abstract Vinylacetylene 1 undergoes reactions with dienophiles by a mechanism involving initial addition of acids to the triple bond, cycloaddition, and elimination of acid.

Rearrangements in polysubstituted cyclohexadienyl carbonium ions

Abstract Allyl migration in the 2,6-di-t-butyl-1,4-dimethylcyclohexadienyl carbonium ion initially proceeds by an apparently normal [1,2] shift to give the expected aromatic product. In moderately concentrated acid, however, the initial rearrangement product undergoes further rearrangements in which migration of a methyl group rather than an allyl group is the major process. This is accounted for by assuming that protonation occurs most rapidly at the position between the two t-butyl groups, thus minimizing steric strain between the substituents on the aromatic ring. Studies on migration of a deuterium labelled allyl group indicate that the allyl group can undergo processes involving allylic inversion as well as [1,2] shifts.

Triptycene-like behaviour of tertiary 9,10-dihydro-9-amthrols

Abstract Secondary alcohols in the 9,10-dihydro-9-anthrol series frequently undergo acid-catalyzed elimination and substitution reactions more rapidly than do corresponding tertiary alcohols - a phenomenon attributed to predominant existence of the tertiary alcohols in triptycene-like conformations with the hydroxy groups in pseudoequatorial positions.

The bromoketone-phenol rearrangement

Abstract Reaction of ketone 1 with phosphorus pentabromide or bromine results in bromination (or dibromination) at C-4. The resulting α-bromoketones rearrange rapidly in acid solutions to yield phenols 2 and 3 .

The observation of a thermal ‘double aromatization’ process in a hydrocarbon with fused blocked aromatic rings

On heating above 150 °C, compound (1), the first reported example of a hydrocarbon with fused blocked aromatic rings, rearranges to form 9-ethylanthracene, with simultaneous aromatization of two non-aromatic rings.

Catalysis of cleavage of di-β-naphthyl ether by electron-donating agents: an explanation for the effectiveness of phenols as promoters for coal conversion

1,3,5-Trimethoxybenzene, 1,2-dimethoxynaphthalene, and 1,4-dimethoxynaphthalene are ineffective as catalysts for the hydrogenolysis of di-β-naphthyl ether in tetralin at 450 °C. However, mixtures of these polyethers with phenol are appreciably more effective catalysts than is phenol itself. Mixtures of the dimethoxynaphthalenes with acetic acid or 1,1,1-trifluoroethanol have catalytic ability, even though the individual components are inactive. It is suggested that both electron-donating ability and acidity are factors determining catalytic activity, and a mechanism is proposed involving electron transfer from the catalyst to the protonated diaryl ether.

Unusual regiochemistry in the hydroboration of 3,3-dibenzylcycloalkenes

Abstract Reaction of 3,3-dibenzylcycloalkenes with diborane results in predominant attack by boron at the more crowded ends of the double bonds.

An extraordinarily rapid [1,5] benzyl shift in a molecule with a ring system consisting entirely of fused blocked aromatic rings

Dehydrobromination of the dibromobicyclic ketone (4) at 0 °C resulted in the formation of ketone (5); the remarkably rapid [1,5] benzyl shift in this reaction is attributed to formation and rearrangement of ketone (2), a unique example of a molecule with a ring system consisting entirely of fused blocked aromatic rings.