钒氧基和亚氨基配合物:V(NC 6 H 4 Me)(O t Bu)3(1),V(NC 6 H 4 Me)Cl 3(2),V(O)(O t Bu)3(3),V(O)(O i Pr)3(4),V(O)(acac)2(5)是对称碳二亚胺(RNCNR,其中R =环己基,异丙基和对甲苯基)复分解的催化剂)。在138℃下,在p二甲苯使用络合物5摩尔%1 - 5中,上述碳二亚胺的复分解,以非对称的碳二亚胺:Ñ -环己基,Ñ ' - p -tolylcarbodiimide(6),Ñ -异丙基,Ñ ' - p -tolylcarbodiimide(7),Ñ -环己基,Ñ '-isopropylcarbodiimide(8) 。取决于所使用的催化剂,在数分钟至数小时内达到碳二亚胺的平衡混合物。从气相色谱获得的产率为32%至70%。络合物2是最有效的催化剂,其周转频率大于100 h -1。羰基配合物(3– 5
Iminophosphorane Cl3PNAr (Ar =
2-fluorophenyl) is an active carbodiimide metathesis catalyst and the
cycloaddition product, a 1,3-diaza-2-phosphetidine, is an intermediate in
the reaction.
Catalytic Double-Bond Metathesis without the Transition Metal
作者:Stephen A. Bell、Tara Y. Meyer、Steven J. Geib
DOI:10.1021/ja020494v
日期:2002.9.1
Iminophosphoranes of the type X3P=NR (X=Cl, pyrrolyl; R=alkyl, aryl) catalytically metathesize C=N bonds of carbodiimides via an addition/elimination mechanism that, despite the lack of d orbital participation in P-N bonding, conserves the key features of metal-catalyzed olefin metathesis. Diazaphosphetidine intermediates, produced by the formal [2+2] addition of carbodiimides to the P=N bond, have been isolated and characterized. All phosphorus-containing species in the complex catalytic reaction mixtures have been identified and their origins explained. The kinetics of addition of diisopropylcarbodiimide to Cl3P=NPl and subsequent elimination were studied, and rate constants were determined: k(add)=1.7x10(-3) (+/-0.1x10(-3)) M s(-1) and k(elim)=4.0x10(-4) (+/-0.3x10(-4)) s(-1). The rate of these reactions corresponds well with the observed catalytic TOF of 1.44 TO/P/h.
Site-Selective Deoxygenative Amination of Azine <i>N</i>-Oxides with Carbodiimides under Catalyst-, Activator-, Base-, and Solvent-Free Conditions
作者:Bikash Kumar Sarmah、Monuranjan Konwar、Animesh Das