Efficient microwave-assisted synthesis of ellipticine through N-(1,4-dimethyl-9h-carbazol-3-ylmethyl)-n-tosylaminoacetaldehyde diethyl acetal

The long-lasting problematic low yield in the D-ring cyclization of ellipticine (1a) was dramatically improved through N-(1,4-dimethylcarbazol-3- ylmethyl)-N-tosylaminoacetaldehyde diethyl acetal with microwave irradiation. The overall yield of 1a starting from indole was significantly increased by 25-fold. This new approach is superior to reported methods in yields and, reaction time, and it provides efficient access to a broad spectrum of ellipticine derivatives.