Am. Strocker et al., USE OF A CONVERTIBLE ISOCYANIDE FOR GENERATION OF UGI REACTION DERIVATIVES ON SOLID SUPPORT - SYNTHESIS OF ALPHA-ACYLAMINOESTERS AND PYRROLES, Tetrahedron letters, 37(8), 1996, pp. 1149-1152
The Ugi four component condensation employing 1-isocyanocyclohexene as
a convertible isocyanide has been adapted to solid supported synthesi
s. Using Wang or Rink resin and a linker derived from succinic anhydri
de, Ugi reactions proceeded smoothly. The products were then converted
under acidic alcohol conditions to esters, acids, and to pyrroles via
1,3-dipolar cycloadditions to an acetylene. The intermediate in both
transformations is a 1,3-oxazolinium-5-one arising from cycloeliminati
on of the cyclohexenamide from the Ugi product.