Isoxazolinyl spironucleosides by nitrile oxide cycloadditions to7-methylenepyrrolo[1,2-c] pyrimidin-1(5h)‎-one

Abstract EN

1,3-Dipolar cycloaddition of TBDPS substituted 6, 7-dihydro-5-hydroxy-3-methoxy-7- Methylenepyrrolo [1, 2-c] pyrimidin-1 (5H)-one with methoxycarbonyl- and cyanonitrile oxide proceed with complete regioselectivity, the approach of the dipole taking place predominantly from the less sterically hindered side of the dipolarophile.

The isoxazolinyl spironucleoside, bearing a primary hydroxymethyl group in C-3 position of the isoxazolinyl ring, was prepared in two steps from the major isoxazoline.

The deprotection of cyanosubstituted spiroisoxazoline furnished the α, β-unsaturated oxime.