Syntheses and Stability of Alkynyl S,N-Acetals Derived from 2-Propynals
摘要:
Two types of synthetic methods for S, N-acetals derived from 2-propynals were described. Thioformamides, lithium acetylides, and alkylating agents were the key substrates. In the first method, methylation of thioformamides with MeOTf followed by reacting with lithium acetylides led to the title compounds. As an alternative method, the direct addition of lithium acetylides to thioformamides gave lithium thiolates, which was then alkylated. With these two methods, a wide range of derivatives including bis-S, N-acetals were provided, and their stability was influenced by the substituents at the alkynyl carbon atom. The introduction of silyl group enhanced the stability effectively.
Two types of synthetic methods for S, N-acetals derived from 2-propynals were described. Thioformamides, lithium acetylides, and alkylating agents were the key substrates. In the first method, methylation of thioformamides with MeOTf followed by reacting with lithium acetylides led to the title compounds. As an alternative method, the direct addition of lithium acetylides to thioformamides gave lithium thiolates, which was then alkylated. With these two methods, a wide range of derivatives including bis-S, N-acetals were provided, and their stability was influenced by the substituents at the alkynyl carbon atom. The introduction of silyl group enhanced the stability effectively.
Synthesis and Properties of 1-Methylthiopropargylammonium Salts and Their Use as Key Precursors to Sulfur-Containing Enediynes
作者:Toshiaki Murai、Kozue Fukushima、Yuichiro Mutoh
DOI:10.1021/ol7024923
日期:2007.12.1
N-acetals with methyl triflate. Reactions of the 1-methylthiopropargylammonium salts with Grignard reagents gave propargyl sulfides or allenyl sulfides, whereas the reaction with organocopperreagents led to exclusive formation of allenyl sulfides regardless of the nature of substituents on the acetylenic carbon. The salts undergo self-dimerization reactions when treated with organolithium and lithium