1.4-Addition of 1.1.2.2-tetrachlorodimethyldisilane to 1.4-diaza-1.3-dienes, synthesis and molecular structure of 1.6-disila-2.5-diaza-1.1.6.6-tetrachloro-1.6-dimethyl-2.5-di-p-tolyl-3.4-diphenyl-hexa-3-ene
摘要:
Reaction of 1.1.2.2-tetrachlorodimethyldisilane (4) with 1.4-diazadienes like benzildianil (1), benzildi-p-tolil (2) and benzildi-p-anisil (3) leads to a 1.4-addition product of the disilane under cleavage of the Si-Si bond (1a, 2a, 3a). The structure of 2a was determined by X-ray crystallography (crystal data: monoclinic, P2(1)/n, a = 14.661(4), b = 12.283(2), c = 17.564(5) Angstrom, beta = 103.13 degrees, Z = 4, R = 0.0585 for 5992 independent reflections). Surprisingly, 2a was found to be in the cis-configuration with almost C-2 symmetry and a torsion angle of only 13 degrees. Owing to statistical disorder, some bond lengths are not in the expected range.
Using tetraaryllead compounds (PbAr4) as arylating reagents, isocyanides undergo selective diarylation in the presence of palladium catalysts such as Pd(OAc)(2) or Pd(PPh3)(4) to afford imines and/or alpha-diimines based on the isocyanide employed. With aliphatic isocyanides, imines are obtained preferentially, whereas alpha-diimines are formed in the case of electron-rich aromatic isocyanides. The differences in imine/alpha-diimine selectivity can be attributed to the stability of imidoylpalladium intermediates formed in this catalytic reaction. Compared with other arylating reagents, tetraaryllead compounds are excellent candidates for use in the selective transformations to imines and/or alpha-diimines, especially in terms of inhibiting the oligomerization of isocyanides, which results in a lower product selectivity in many transition-metal-catalyzed reactions of isocyanides.
MEHROTRA K. N.; SINGH G., SYNTHESIS, 1980, NO 12, 1001-1004
作者:MEHROTRA K. N.、 SINGH G.
DOI:——
日期:——
SINGH, GEETA;MEHROTRA, KAILASH, NATH, HETEROCYCLES, 1981, 16, N 8, 1341-1344
作者:SINGH, GEETA、MEHROTRA, KAILASH, NATH
DOI:——
日期:——
MEHROTRA, K. N.;SINGH, I. S.;ROY, J., SYNTHESIS, BRD, 1985, N 1, 81-83
作者:MEHROTRA, K. N.、SINGH, I. S.、ROY, J.
DOI:——
日期:——
1.4-Addition of 1.1.2.2-tetrachlorodimethyldisilane to 1.4-diaza-1.3-dienes, synthesis and molecular structure of 1.6-disila-2.5-diaza-1.1.6.6-tetrachloro-1.6-dimethyl-2.5-di-p-tolyl-3.4-diphenyl-hexa-3-ene
作者:U. Herzog、G. Roewer、B. Ziemer、B. Herrschaft
DOI:10.1016/s0022-328x(96)06823-4
日期:1997.4
Reaction of 1.1.2.2-tetrachlorodimethyldisilane (4) with 1.4-diazadienes like benzildianil (1), benzildi-p-tolil (2) and benzildi-p-anisil (3) leads to a 1.4-addition product of the disilane under cleavage of the Si-Si bond (1a, 2a, 3a). The structure of 2a was determined by X-ray crystallography (crystal data: monoclinic, P2(1)/n, a = 14.661(4), b = 12.283(2), c = 17.564(5) Angstrom, beta = 103.13 degrees, Z = 4, R = 0.0585 for 5992 independent reflections). Surprisingly, 2a was found to be in the cis-configuration with almost C-2 symmetry and a torsion angle of only 13 degrees. Owing to statistical disorder, some bond lengths are not in the expected range.