Synthesis and 1,3-dipolar cycloadditions of a new enantiopure cyclic nitrone

(1R,4R,5R)-1,3,4-Triphenyl-7-[(R)-1-phenyl-ethyl]-2-oxa-3,7-diaza-spiro-[4.5]decan-10-one

In the title compound, C₃₃H₃₂N₂O₂, the polysubstituted piperidine ring adopts a chair conformation. The isoxazolidine ring is in an envelope conformation. In the crystal structure, intra- and inter­molecular C—H⋯π inter­actions involving the phenyl rings are observed.

Asymmetric Synthesis of the Azabicyclic Core of the Stemona Alkaloids

A general strategy for the construction of the 1-azabicyclo[5.3.0]decane core of Stemona alkaloids is developed. Our diversity-oriented approach exploits 1,3-dipolar cycloaddition of five-membered cyclic nitrones to C(6) olefins, followed by N-O reductive cleavage and azepine closure. The use of various enantiopure pyrroline N-oxides allows for a practical, stereoselective preparation of several putative precursors of different Stemona alkaloids.

Water Exclusion Reaction in Aqueous Media: Nitrone Formation and Cycloaddition in a Single Pot

[reaction: see text] The formation of nitrone (a water exclusion reaction) in aqueous media using surfactant and subsequent cycloaddition in the same pot, a new example of green chemistry, is reported. The control of regioselectivity favors the formation of trans-5-substituted isoxazolidine. This work not only may lead to an environmentally benign system but also will provide a new aspect of reactions in water.