2958-62-5Relevant articles and documents
A P?P Bond as a Redox Reservoir and an Active Reaction Site
Kim, Yeong-Eun,Lee, Yunho
, p. 14159 - 14163 (2018)
The carbonylation of a nickel(II) anilido species 2 led to the formation of a dinickel(0)–CO complex (P2P-PP2){Ni(CO)}2 3 with a P?P bond along with isocyanate generation. In this reaction, the central phosphide moiety of an anionic PPP ligand (PPP?=?P[2-PiPr2C6H4]2) acts as a single-electron donor to form a P radical. Alternatively, 3 can be synthesized from the reduction of (PPP)NiCl (1) in the presence of CO; thus, the reaction proceeds by radical coupling of a .P?Ni0?CO species. The reverse reaction occurred to generate 1 when 3 was treated with AgCl. Since the P?P bond is light-sensitive, its homolysis is possible and was explored by EPR spectroscopy and DFT analysis. Finally, various bond-activation reactions of 3 occurred under visible-light conditions, thus indicating that a P?P bond can act as an active reaction site.
Di-tert-butyl dicarbonate and 4-(dimethylamino)pyridine revisited. Their reactions with amines and alcohols
Basel, Yochai,Hassner, Alfred
, p. 6368 - 6380 (2007/10/03)
The reaction of BOC2O in the presence and absence of DMAP was examined with some amines, alcohols, diols, amino alcohols, and aminothiols. Often, unusual products were observed depending on the ratio of reagents, reaction time, polarity of solvent, pK(a) of alcohols, or type of amine (primary or secondary). In reactions of aliphatic alcohols with BOC2O/DMAP, we isolated for the first time carbonic-carbonic anhydride intermediates; this helps explain the formation of symmetrical carbonates in addition to the O-BOC products. In the case of secondary amines, we succeeded to isolate unstable carbamic-carbonic anhydride intermediates that in the presence of DMAP led to the final N-BOC product. The effect of N-methylimidazole in place of DMAP was also examined.
Preparation of isocyanates from primary amines and carbon dioxide using Mitsunobu chemistry
Saylik, Dilek,Horvath, Michael J.,Elmes, Patricia S.,Jackson, W. Roy,Lovel, Craig G.,Moody, Keith
, p. 3940 - 3946 (2007/10/03)
Primary alkylamines 1 and hindered arylamines 1 give high yields of isocyanates 5 when reacted with carbon dioxide and the Mitsunobu zwitterions 4 generated from dialkyl azodicarboxylates and Bu3P in dichloromethane at - 78°C. Use of Ph3P still gave high yields of isocyanates from reactions of primary alkylamines, but only low yields were obtained from reactions of aromatic amines. Reactions which failed to give high yields of isocyanates gave either carbamoylhydrazines 6 and/or dicarbamoylhydrazines 10 and/or triazolinones 7. The triazolinones were shown to arise from reactions of reactive aryl isocyanates with the Mitsunobu zwitterion. The carbamoylhydrazines were shown not to arise from reaction of isocyanate with reduced dialkyl azodicarboxylates, and a mechanism for their formation is proposed. Single-crystal X-ray analyses confirmed the structures of 6, 7, and 10.