A new method for preparing 2‐mercaptoacetamide and N‐alkyl‐2‐mercaptoacetamides has been described. Electronic spectra of sixteen N‐alkyl and N‐aryl‐2‐mercaptoacetamides have been compared with corresponding substituted acetamides and discussed. The results reveal the possibility of an intra‐molecular hydrogen‐bonding between NH hydrogen and sulphur of SH group.

SummaryThe Diels–Alder reaction of the 2-phosphaindolizine-η1-P-aluminium(O-menthoxy) dichloride complex with dimethylbutadiene was investigated experimentally and computationally. The >C=P– functionality of the complex reacts with 2,3-dimethylbutadiene with complete diastereoselectivity to afford [2 + 4] cycloadducts. Calculation of the model substrate, 3-methoxycarbonyl-1-methyl-2-phosphaindolizine-P-aluminium(O-menthoxy) dichloride (7a), at the DFT (B3LYP/6-31+G*) level reveals that the O-menthoxy moiety blocks the Re face of the >C=P– functionality, due to which the activation barrier of the Diels–Alder reaction of 7a with 1,3-butadiene, involving its attack from the Si face, is lower. It is found that in this case, the exo approach of the diene is slightly preferred over the endo approach.

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