3-substituted furan systems can be obtained by alkylation of 3-lithium furans with various electrophiles in the presence of hexamethylphosphoric acid triamide in good yields. The 2- or 5-position of 3-methyl furan is blocked with high regioselectivity by silylation. After metalation and alkylation of the remaining free α-position and subsequent desilylation the 2, 3-and 2, 4-disubstituted furans are obtained. These methods are used to synthesize the ...
