Terf-Butyl isocyanate

Benzylaminoethylamine (123), 2-chloroacetaldehyde, terf-butyl isocyanate, and formic acid gave 4-benzyl-/V-/er/-butyl-1-formyl-2-pipcrazinccarboxamidc (124) (MeOH—H20, 23°C, 3 days 60%).1533... 

A high yield of isocyanate 469 was obtained by carbonylating 4-amino-4-(2-tert-butoxycarbonylethyl)-heptanedioic acid di-terf-butyl ester 468 with triphosgene in diethyl ether [321]. 

Density functional theory (DPT) calculations were performed to elucidate the relative energies of the intermediates and products of this reaction. There are two reaction pathways that could generate the bis(imido) product 9 and the oxo-imido species 8 from U(N Bu)2(I)2(OPPh3)2 (Paths 1 and 2, Scheme 14.3). See color plate section. The first pathway involves the [2 - - 2] cycloaddition of the C = N bond of the aryl isocyanate to form an AQV-bound ureato intermediate (13), which can isomerize to form species 14 with the -NPh group trans to the terf-butyl imido moiety. Compound 14 can then eliminate BuNCO to generate the unsymmetrical bis(imido) complex 9 (top line in Scheme 14.2). Alternatively, AO-bound carbamate intermediates 15 and 16 could form that result from the [2 + 2] cycloaddition of the C = O bond of the aryl isocyanate across the U = N imido bond. Elimination of a substituted carbodiimide would generate the oxo-imido complex 8 (bottom line in Scheme 14.2). 

Solns. of N,N-di-terf-butylsulfinodiimine and fluorosulfonyl isocyanate in dry methylene chloride dropped simultaneously at -78° into vigorously stirred methylene chloride, and warmed to room temp. N- r/-butyl-N -(fluorosulfonyl)-sulfinodiimine. Y 77%. F. e. s. R. Appel and M. Montenarh, B. 109, 2437 (1976). 

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