Tri-tert-butylphosphine tetrafluoroborate → methyl (1aRS,7bSR)-5-(N-{2-[(Z)-3-(tert-butyldimethylsilanyloxy)-2-methylprop-1-enyl]-4-fluorobenzenesulfonyl]-N-methoxycarbonyl-amino}-1,1a,2,7b-tetrahydrocyclopropa[c]chromene-4-carboxylate

Participants

Reaction Conditions

Reaction Steps

A mixture of methyl (1aRS,7bSR)-5-[N-(2-bromo-4-fluorobenzenesulfonyl)-N-(methoxy-carbonyl)amino]-1,1a,2,7b-tetrahydrocyclopropa-[c]chromene-4-carboxylate (Intermediate 65, 0.257 g), tert-butyl-dimethyl-((Z)-2-methyl-3-tributylstannanylallyloxy)silane (0.475 g), tris(dibenzylideneacetone)dipalladium(0) (0.023 g) and tri-tert-butylphosphonium tetrafluoroborate (0.015 g) in dioxane (8 mL) and DMSO (0.8 mL) was stirred and heated at 90° C. under nitrogen for 1 hour. Further tris(dibenzylideneacetone)dipalladium(0) (0.023 g) and tri-tert-butylphosphonium tetrafluoroborate (0.015 g) were added and heating was continued for a further 40 minutes. After cooling, the mixture was diluted with ethyl acetate, washed with water, dried (Na2SO4) and filtered. The filtrate was concentrated in vacuo and the residue was purified by chromatography on silica, eluting with a mixture of ethyl acetate and cyclohexane with a gradient of 0-20% to give methyl (1aRS,7bSR)-5-(N-{2[(Z)-3-(tert-butyldimethylsilanyloxy)-2-methylprop-1-enyl]-4-fluorobenzenesulfonyl]-N-methoxycarbonyl-amino}-1,1a,2,7b-tetrahydrocyclopropa[c]chromene-4-carboxylate (0.231 g) as a colourless gum.

Provenance & Evidence