DEAN F. M.; JOHNSON R. S., J. CHEM. SOC. PERKIN TRANS., PART 1, 1981, NO 1, 224-230
作者:DEAN F. M.、 JOHNSON R. S.
DOI:——
日期:——
The alkylation and ring-expansion of chromones by diazoalkanes; reluctance of oxygen to engage in sigmatropic shifts
作者:Francis M. Dean、Robert S. Johnson
DOI:10.1039/p19810000224
日期:——
In general, chromones activated by electron-withdrawing groups at position 3 are alkylated (at position 2) by diazoalkanes in the same manner as the isomeric coumarins. For example, 6-methylchromone-3-carbonitrile (3a) is converted by diazoethane into 2-ethyl-6-methylchromone-3-carbonitrile (3c). 2-Diazopropane affords cyclopropane by-products as well, and a 3-formyl group usually suffers homologation