反应详情

Scheme C-6 illustrates the synthesis of the maleimide pyrazole scaffold C-63 wherein R4 is hydrogen. The synthesis starts with the condensation reaction of bromomaleic anhydride B77 with 2,4-dimethoxybenzylamine in acetic acid and acetic anhydride, giving rise to intermediate B76. The maleimide B78 is then treated with 4′-fluoroacetophenone in the presence of catalytic amount Pd2(dba)3 and sodium t-butoxide to form the fluoroacetophenone substituted maleimide B79. The B79 is treated with tert-butoxybis(dimethylamino)methane to yield the a-ketoenamine B80. The a-ketoenamine B80 is condensed with hydrazine to form the maleimide pyrazole skeleton B81. The 2,4-dimethoxybenzyl group protecting group is optionally removed with ceric ammonium nitrate (CAN) to give compound C-63.