Sequential one-pot synthesis of N-sulfonyl spiroaziridine oxindoles from spiroepoxy oxindoles

The N-sulfonyl spiroaziridine oxindole is a recently developed versatile precursor in the synthesis of a wide range of 3,3-disubstituted spirooxindoles. It is usually prepared in three steps from isatin and needs costly and hardly available sulfinimides and hazardous peracid. A sequential and one-pot direct strategy for the synthesis of terminal N-sulfonyl spiroaziridine oxindoles has been developed under ambient conditions with excellent yields (up to 95%) from easily accessible spiroepoxy oxindoles by regioselective amination with aqueous ammonia and a subsequent ring enclosure reaction of the resulting 1,2-amino alcohol using easily available sulfonyl chloride and a base. Other salient features of the protocol include inexpensive substrate requirement and the ease of isolation of the desired product by performing single column chromatographic purification after two consecutive steps.

Recent trends in the direct oxyphosphorylation of C-C multiple bonds

Due to the wide importance of β-phosphorylated ketones as key building-blocks in the fabrication of various pharmaceutically active organophosphorus compounds, finding new and truly efficient methods for their preparation from simple, low-cost and ubiquitous feedstock materials within a single click is an interesting subject in organic synthesis. Recently, oxyfunctionalization of carbon-carbon multiple bonds has arisen as a straightforward and versatile tool for the synthesis of complex organic molecules from the simple and easily accessible alkenes/alkynes via a single operation. In this context, oxyphosphorylation of alkenes/alkynes with P(O)-H compounds has attracted considerable attention as a unique procedure for the construction of β-phosphorylated ketones. In this review, we outline the recent advances and developments in this fast-growing research field with particular emphasis on the mechanistic aspects of reaction.