Scott Searles

Observation on the synthesis of allenes by homologation of alk-1-ynes

An investigation is reported on the homologation of alk-1-ynes to allenes by the cuprous bromide-catalyzed reaction with formaldehyde and di-isopropylamine, including extension to an aromatic acetylene and a diacetylene. Optimization of yields was studied. A mechanism is proposed involving an intermediate hydrido-cuprate species derived from a 1:1 Mannich base–cuprous bromide π-complex. The mechanism is supported by labelling experiments and observed substituent effects.

Stereochemical effect in the mutagenicity of the aflatoxicols toward Salmonella Typhimurium

The mutagenicities of [1R] and [1S] aflatoxicol were measured using the Salmonella microsome test. In strain TA100 the [1R] form (unnatural aflatoxicol, aflatoxicol B) had a mutagenic potency approximately four times that of the [1S] epimer (natural aflatoxicol, aflatoxicol A, Ro) in the presence of S-9 liver microsomal fraction. The order in mutagenic potency compared to some other toxicologically important aflatoxins was as follows: B1 greater than [1R] approximately equal to G1 much greater than [1S] much much greater than B2. Thus, the trans relationship between the vinyl ether and hydroxyl groups leads to greater mutagenicity than the cis relationship. This may be important in the elucidation of stereochemical structure-activity relationships for the aflatoxins.