Selenium tetrachloride with amines

The ene addition of ethyl propiolate to P-pinene is catalysed by aluminium chloride as expected, the reaction is stereospecific and affords (545) in 82 % yield after 2 days at room temperature in benzene solution. Other 1,1-dialkylethylenes reacted similarly, but 1,2-dialkyl- and monosubstituted ethylenes, however, afforded products of stereospecific [2 +2] addition presumably short-lived dipolar intermediates are formed in the non-ene processes. Reaction of selenium tetrachloride with two equivalents of t-butylamine or toluene-p-sulphonamide in dichloromethane in the presence of four equivalents of an amine base produces solutions thought to contain iminoselenium compounds RN=Se=NR (R = Bu or Ts). Both compounds reacted with P-pinene to afford the allylic amination products (546). An even more... 

Following the report last year of the first vicinal oxyamination of olefins using aminated derivatives of osmium tetroxide. Sharpless has extended this analogy to oxidations involving selenium dioxide. Two aza analogues of selenium dioxide have been prepared by either the reaction of selenium tetrachloride with the amine or... 

Selenium di-imides (132) were formed in methylene chloride solution from selenium tetrachloride with t-butylamine or sulphonamides and also from selenium metal with anhydrous Chloramine-T. They were found to be efficient reagents for the allylic amination of alken and alkynes. The first examples of selenium imides (133) were synthesized from diaryl selenides and Chloramine-T, from... 

Tellurium tetrachloride in combination with a strong amine base effected the mild dehydrosulfurization of thioamides to nitriles. Treatment of the thioamides (60) with tellurium tetrachloride and triethylamine in chloroform at room temperature formed nitriles (61) in excellent yield. Using selenium tetrachloride, a similar reaction also occurred in a little lower yield and accompanied by the formation of the 1,2,4-thiadiazole (63). In a plausible mechanism, some of the 1 1 adduct (61) undergoes a further addition reaction with another thioamide molecule prior to the degradation reaction to nitrile, leading to the formation of the 1,2,4-... 

The synthesis of ureas by reaction of ammonia or aliphatic primary and secondary amines with carbon monoxide at atmospheric pressure under selenium catalysis is noted. The intermediate salt can be oxidized to the sym-urea, or an exchange can be effected with a second amine, leading to unsym-ureas, as shown in Scheme 34. Ureas are readily dehydrated to carbodi-imides by the triphenylphosphine-carbon tetrachloride-triethylamine combination... 

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