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A practical process for recycling the tert-butanesulfinyl group upon deprotection of N-tert-butanesulfinyl amines has been achieved. Treatment of N-tert-butanesulfinyl amines with HCl in cyclopentyl methyl ether results in complete conversion to tert-butanesulfinyl chloride and the corresponding amine hydrochloride salt, which is isolated by filtration in analytically pure form and in quantitative yield. Treatment of the resulting sulfinyl chloride solution with aqueous ammonia then provides analytically pure tert-butanesulfinamide in 97% yield. Alternatively, the tert-butanesulfinyl chloride solution can be treated with ethanol and catalytic quinidine as a sulfinyl transfer catalyst to provide a cyclopentyl methyl ether solution of ethyl tert-butanesulfinate with 88% ee. Addition of NaNH(2) in ammonia followed by simple trituration of the product with octane provides tert-butanesulfinamide with 99% ee and in 67% overall isolated yield based upon the starting N-tert-butanesulfinyl amine.

Development of enediyne model compounds that produce dehydrotoluene diradicals under acidic media is described. The ionic character of the diradicals is shown to be avoided by the electron-withdrawing groups in the molecules both in benzene and MeOH.

Stable α-alkynylacetic acid derivatives related to cis-enediyne were synthesized and the rate of decarboxylative cycloaromatization of 3,5-difluoro derivative 7c was found to be much faster than that of the corresponding phenyl derivative 7a. The cycloaromatization reaction mechanisms of 7c under various conditions were investigated.

The acyclic enediyne possessing an aminomethyl group was designed and synthesized as a potential substrate for pyridoxal-dependent enzymes. Compound 2 was shown to give cycloaromatized products by the reaction with pyridoxal or isonicotinaldehyde via the toluene biradical intermediate.

Diethyl α-methoxy-α-alkynylmalotate derivatives of cis -enediynes were synthesized and they produced toluenebiradicals via the reaction cascade triggered by ester hydrolysis. Deuterium labeling studies suggested that the reaction involved the self quenching process by fairly fast disproportionation of toluene biradicals producing zwitterionic species.

Diethyl α-methoxy-α-alkynylmalotate derivatives of cis -enediynes were synthesized and they produced toluenebiradicals via the reaction cascade triggered by ester hydrolysis. Deuterium labeling studies suggested that the reaction involved the self quenching process by fairly fast disproportionation of toluene biradicals producing zwitterionic species.

Development of enediyne model compounds that produce dehydrotoluene diradicals under acidic media is described. The ionic character of the diradicals is shown to be avoided by the electron-withdrawing groups in the molecules both in benzene and MeOH.