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Dicobalt hexacarbonyl complexes of alkynyl imines were allowed to react with ketenes via Staudinger reaction. Sequential [2 + 2] cycloaddition/Pauson-Khand reaction led to structurally new fused-tricyclic beta-lactams and fused-azabicyclic cyclopentenones. Chemoselectivity, scope, and limitation of the process were investigated.

UV irradiation in the presence of thiol enables the performance of highly efficient aliphatic amines racemization, under mild conditions at 30 degrees C. The reaction proceeds via the reversible generation of prochiral alpha-aminoalkyl radicals. The latter may result either from a redox process between the thiyl radical and the amine or from direct hydrogen atom abstraction by thiyl radical. As hydrogen atom donor, the thiol plays a crucial role. While the racemization of both primary and secondary amines were fast processes, the racemization of tertiary amines was sluggish. A tentative rationale is based on the photostimulated amine-catalyzed oxidation of the thiol into the corresponding disulfide, which makes the hydrogen atom donor concentration in the reaction medium drop up to trace amount at a rate that depends on the nature of the amine.

Optimization of the kinetic resolution of 2-amino-4-phenyl-butane was achieved at 80 degrees C using CAL-B-catalyzed aminolysis of carboxylic acids and their ethyl esters. The reactions carried out with long chain esters and the corresponding acids as acyl donors proceeded with remarkably high enantioselectivity. The use of carboxylic acids as acylating agents led to a marked acceleration of the reaction rate compared to their ester counterparts. Lauric acid led to enantiomeric excesses superior to 99.5% for both the remaining amine and the corresponding lauramide at 50% conversion (reached in 3 h). These optimized conditions were applied to the resolution of a series of aliphatic and benzylic amines.