The borrowing hydrogen approach allows the direct utilization of non-activated alcohols as alkylating agents. A readily available, air and moisture stable ruthenium complex proves to be a particularly effective hydrogen autotransfer catalyst for the alkylation of various indoles or ketones with poorly reactive alcohols.

Abstract

A diaminocyclopentadienone ruthenium complex has proven to be a highly effective catalyst for the alkylation of indoles or ketones with poorly reactive alcohols. The catalyst is readily available, air and moisture stable and exhibits wide functional group tolerance. The environmentally benign procedure follows a borrowing hydrogen mechanism and requires no excess of either component. Various indoles and ketones are selectively monoalkylated in high yield.