Eugene Cheung

Asymmetric induction in the solid state photochemistry of an α-mesityl-acetophenone derivative through the use of ionic chiral auxiliaries

Abstract Irradiation in the crystalline state of salts formed between α-mesitylacetophenone- p -carboxylic acid and a variety of optically pure amines—the so-called ‘ionic chiral auxiliary’ approach to asymmetric synthesis—leads to the corresponding 2-indanol in excellent yield and in high enantiomeric excess. X-Ray crystallography reveals the source of the enantioselectivity.

Linearly conjugated benzocyclohexadienone photochemistry in the solid state: ionic chiral auxiliary mediated asymmetric induction

Abstract Asymmetric induction in the photochemistry of a linearly conjugated benzocyclohexadienone derivative has been achieved for the first time through the use of the solid state ionic chiral auxiliary method. Enantiomeric excesses as high as 70–80% at reasonable conversions are readily attainable. Crystal structures for both reactant and product are reported.

An ionic chiral auxiliary-induced regioselective and enantioselective Yang photocyclization reaction in the crystalline state

Abstract cis -9-Decalyl aryl ketones undergo Yang photocyclization in solution to afford an approximately 1:1 mixture of two regioisomeric racemic cyclobutanols. In contrast, irradiation in the crystalline state in the presence of various ionic chiral auxiliaries leads to a single cyclobutanol in >98% enantiomeric excess. X-Ray crystallography reveals the source of the regio-, diastereo- and enantioselectivity.

Asymmetric induction through the use of remote covalent and ionic chiral auxiliaries in the solid state photochemistry of 2-benzoyladamantane-2-carboxylic acid derivatives

Abstract Attachment of chiral auxiliaries to 2-benzoyladamantane-2-carboxylic acid, either covalently through ester formation with optically pure alcohols, or ionically via salt formation with optically pure amines, leads to substrates whose irradiation in the crystalline state affords chiral rearranged photoproducts in ≥96% diastereo- and enantiomeric excess.

Latent chemical behavior revealed in the crystalline state: novel photochemistry of a cis-9-decalyl aryl ketone

The case of a ketone whose photochemistry in solution is markedly different from that observed in the crystalline state is reported.