“…At the time of this important discovery of CO generation from 20a, various CO surrogates were known, including formic acid, [48][49][50] paraformaldehyde, 50) N,N-dimethylformamide (DMF), 51) chloroform, 52) aldehydes, [53][54][55][56] metal carbonyl complexes, 57) acid chlorides, 58) and silacarboxylic acids. 59) Alkyl formates 60) had been also reported to act as CO surrogates.…”