A Preparation of Alkyl or Alkenyl N,N-Dimethylchalcogenocarbamates and Their One-Step Conversion into Symmetrical Dialkyl or Dialkenyl Dichalcogenides

Abstract

Alkyl or alkenyl N,N-dimethylchalcogenocarbamates were easily prepared by a stepwise treatment of bis(N,N-dimethylcarbamoyl) dichalcogenides with NaH or NaBH4, followed by various alkylating agents or acetylenes bearing electron-withdrawing substituents. The one-step conversion of alkyl or alkenyl N,N-dimethylselenocarbamates or N,N-dimethyltellurocarbamates into the corresponding symmetrical dialkyl or dialkenyl dichalcogenides was also achieved efficiently by treating with SnCl4.

Light-induced reactions of 2,2-bis(2,2-dimethylethyl)-6H -1,3-oxaselenin-6-one in methanol

“…The MSand NMR-data of diselenide 4 match those reported in the literature, 8 while those for 5 and 6 exhibit the expected changes in both vicinal coupling constants of the olefinic H-and chemical shifts of the olefinic C-atoms. Finally, MS-and NMR-data of 7 are again identical with those reported in the literature.…”

Stannic chloride-induced unsymmetrical CSe bond cleavage of bis(N,N-dimethylcarbamoylseleno)methanes: Novel generation of selenoaldehydes

“…δ = 3.44 ppm ( δ = +0.48 ppm) assigned to the N,Ndimethylcarbamoyl group, and δ = 7.00 ppm (broadening, δ = +0.89 ppm) assigned to the methine proton) with retaining the symmetrical spectral pattern of 1a. These results excluded out the formation of a tight 1a-SnCl 4 complex in the reaction mixture, and a weak coordinating interaction between 1a and SnCl 4 involving an association-dissociation equilibration was suggested [31]. Further standing of the mixture at 25…”

“…• C followed by aerobic exposure at RT according to the previous reports [31]. Subsequently, stepwise treatment of a DMF solution of diselenide 4 with NaH [31,32] and a gem-dihaloalkane 5 (benzal bromide 5a, m-chlorobenzal bromide 5b, pchlorobenzal bromide 5c, 1,1-dibromoethane 5d, dibromomethane 5e, and ethyl dichloroacetate 5f, respectively) efficiently afforded air-stable bis(N,Ndimethylcarbamoylseleno)methanes 1a-f [26], which are regarded as a new class of symmetrical diselenoacetals bearing a N,N-dimethylcarbamoyl group on each selenium atoms.…”

“…Subsequently, stepwise treatment of a DMF solution of diselenide 4 with NaH [31,32] and a gem-dihaloalkane 5 (benzal bromide 5a, m-chlorobenzal bromide 5b, pchlorobenzal bromide 5c, 1,1-dibromoethane 5d, dibromomethane 5e, and ethyl dichloroacetate 5f, respectively) efficiently afforded air-stable bis(N,Ndimethylcarbamoylseleno)methanes 1a-f [26], which are regarded as a new class of symmetrical diselenoacetals bearing a N,N-dimethylcarbamoyl group on each selenium atoms. On the other hand, stepwise treatment of 4 with NaBH 4 with 5a in a mixed solvent of C 2 H 5 OH-DMF (1:1) only gave 1a in 20% yield along with the formation of dibenzyl diselenide as a major product [31], and the use of diisobutylaluminum hydride (DIBAH), in place of NaH, also gave discourageous results. All the results are shown in Table 1.…”

“…We already reported a one-step conversion of alkyl or alkenyl N,N-dimethylselenocarbamates or N,N-dimethyltellurocarbamates into the corresponding symmetrical dialkyl or dialkenyl dichalcogenides by treating with SnCl 4 [31]. However, it is noteworthy that the independent reaction of selenocarbamate 13a with SnCl 4 in the presence of allyltrimethylsilane at 0…”