Investigations into the transition metal catalyzed aziridination of olefins with Bromamine-T as a new source of nitrene is presented in this account. Comparison of Chloramine-T and Bromamine-T in this reaction indicates that the latter is superior as the source of nitrene. Systematic study with several transition metal based catalysts suggests that Cu-halides are the best catalysts. A first report of aziridination under microwave and ultrasound irradiation conditions is also presented. Copper-catalyzed aziridination of methyl cinnamate with Bromamine-T did not proceed at ambient temperature but was effected smoothly under ultrasound irradiation to furnish trans-aziridine selectively, while under microwave irradiation, a mixture of cis and trans isomers, was obtained. It has been demonstrated that aziridination of olefins proceeds smoothly with inexpensive bleaching powder. Preliminary results of Rh-catalyzed benzylic insertion reactions with Bromamine-T are included in this account.

Crystalline microporous aluminosilicates (zeolites) efficiently catalyse the transesterification of P-keto esters with high selectivity under environmentally safe reaction conditions.In connection with our ongoing programme on the synthesis of lignans including Podophyllotoxinl 29, we were in need of various intermediate (3-keto esters 23, 24, 27 and 28. (3-Keto esters represent an important class of organic building blocks2 and are used for efficient synthesis of a number of complex natural products. Several methods exist for their synthesis;3 however, none of them are amenable to the present requirement. In this regard, transesterification,4 an important reaction for synthesis of esters, was chosen. Although many methods are available for the preparation of alkyl benzoylacetates,3b~3~,3e there are no reports on the synthesis of p-keto esters 23, 24, 27 and 28. Transesterification of (3-keto esters especially with allylic alcohols is rather difficult as it is offset by facile decarboxylated rearrangement.5 Even modified Taber's method6a gives only moderate yields of allylic acetoacetates.OMe 29

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