1,8-Diazabicyclo[5.4.0]undec-7-ene (DBU) and microwave-accelerated green chemistry in methylation of phenols, indoles, and benzimidazoles with dimethyl carbonate.

1,8-Diazabicyclo[5.4.0]undec-7-ene (DBU) is a novel and active catalyst in promoting the methylation reaction of phenols, indoles, and benzimidazoles with dimethyl carbonate under mild conditions. Additional rate enhancement is accomplished by applying microwave irradiation. By incorporating tetrabutylammonium iodide, the same microwave reactions can be further accelerated. By combining these acceleration strategies, very slow chemical transformations that take up to several days can be performed efficiently in high yield within minutes. [reaction: see text]