Synthesis of Angiotensin II Receptor Blockers by Means of a Catalytic System for C–H Activation
摘要:
A highly efficient catalytic system for C-H activation has been worked out that involves inexpensive RuCl3.xH(2)O and a specific amount of PPh3. This procedure has been successfully applied to a practical synthesis of angiotensin II receptor blockers (ARBs). The residual ruthenium that existed in the reaction mixture was thoroughly removed by treatment with properly selected metal scavengers. The new process permits ready access to the important class of drugs in a highly atom-economical and sustainable manner.
Metal-free cross-dehydrogenative C–N coupling of azoles with xanthenes and related activated arylmethylenes
摘要:
A metal-free C(sp(3))-H/N-H cross-coupling of azoles with xanthenes and related activated arylmethylenes is presented. Both the use of azoles and the activation pattern of C(sp(3))-H sources are essential for this transformation. In the presence of 2.0 equiv of benzoyl peroxide (BPO), methylenes bearing a heteroatom-bridged bisaryl group reacted with various azolic N-H sources to afford C-N bond forming products in usually excellent or quantitative yields, and the diphenylmethane and methylenes coactivated by a phenyl group and an adjacent heteroatom are less reactive. Mechanistic investigations suggest that a radical/radical cross-coupling pathway might be involved.[GRAPHICS].