Gold carbon-sulfur bond

Hydrothiolation of Allenes The first example of a gold-catalyzed carbon-sulfur bond formation was published by Kraus et al. who synthesized 2,5-dihydrothiophenes by allenyl thiocarbinols [38]. The best results were obtained with AuCI in CH2C12, providing an impressive diastereoselectivity. In the same study, other coin-metal precatalysts were tested but only gold afforded the cydization product. 

The gold-catalyzed formation of a carbon-sulfur bond is not an easy task, given the high strength of Au-S bonds that renders sulfides potent poisons for gold catalysts. Nevertheless, the first example for a gold-catalyzed C-S bond formation was reported in 2006 when Morita and Krause converted various a-thioallenes into the corresponding 2,5-dihydrothiophenes (Scheme 4-118). In this transformation. 

The reaction of [PPN][Au2 CH2P(S)Ph2 2] with HgCl2, followed by T1PF6 treatment, resulted in a rearrangement of the Au-C bonds and compound 6 was isolated. It is an isomer of compound 5 in the cation of which both gold and mercury are linearly coordinated by a carbon and a sulfur atom. The isomers 5 and 6 do not interconvert under reflux inTHF [36]. The transannular gold-mercury distance in the cation of 6 [2.989(1) A] is about 0.1 A shortest than in the cations containing the... 

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