Medium-Sized Heterocycle Synthesis by the Use of Synergistic Effects of Ni-NHC and γ-Coordination in Cycloisomerization
作者:Chun-Yu Ho、Lisi He
DOI:10.1021/jo5008477
日期:2014.12.19
an NHC–NiH catalyst and γ-heteroatom chelation were used together as a basis for 1,n-diene termini differentiation and for nγ-exo-trig (head-to-tail) product selectivity. Heterocycles bearing an exocyclic methylene such as oxepines, thiepines, siloxepines, and oxocanes were synthesized from the corresponding 1,n-dienes by a fine-tuning of the NHC properties. The implication of the underlying hypothesis
Synthetic application of titanabicycles generated from 1,6- or 1,7-dienes, enynes, and diynes and (ν2-propene)Ti(O-i-Pr)2
作者:Hirokazu Urabe、Takeshi Hata、Fumie Sato
DOI:10.1016/0040-4039(95)00727-t
日期:1995.6
The title unsaturated compounds and a stoichiometric amount of (ν2-propene)Ti(O-i-Pr)2 afforded titanabicycles, which, upon hydrolysis, gave substituted cyclopentane and cyclohexane frameworks. The titanacycles could be also intercepted with deuterium, iodine, or carbon monoxide.
Palladium-Catalyzed Asymmetric Diene Cyclization/Hydrosilylation Employing Functionalized Silanes and Disiloxanes
作者:Tao Pei、Ross A. Widenhoefer
DOI:10.1021/jo015724n
日期:2001.11.1
diallylmalonate (1) and other functionalized 1,6-dienes in the presence of a catalytic 1:1 mixture of (N-N)Pd(Me)Cl [N-N = (R)-(+)-4-isopropyl-2-(2-pyridinyl)-2-oxazoline] [(R)-2] and NaBAr(4) [Ar = 3,5-C(6)H(3)(CF(3))(2)] to form the corresponding silylated cyclopentanes in good yield with high diastereoselectivity. The enantioselectivity of cyclization/hydrosilylation of 1 with disiloxanes and functionalized
A series of 1,6-dienes is cyclized to cyclopentene derivatives underneutralconditions with palladium chloride in ethanol or with in situ generated LPd2+ in acetonitrile.
Enantioselective Diene Cyclization/Hydrosilylation Catalyzed by Optically Active Palladium Bisoxazoline and Pyridine−Oxazoline Complexes
作者:Nicholas S. Perch、Tao Pei、Ross A. Widenhoefer
DOI:10.1021/jo0003192
日期:2000.6.1
palladium pyridine-oxazoline complex (N-N)Pd(Me)Cl ¿N-N = (R)-(+)-4-isopropyl-2-(2-pyridinyl)-2-oxazoline (R-5b) and NaBAr(4) (5 mol %) catalyzed the asymmetric cyclization/hydrosilylation of 2 and triethylsilane at -32 degrees C for 24 h to form carbocycle S,S-3 in 82% yield (>95% de, 87% ee) as the exclusive product. Asymmetric diene cyclization catalyzed by complex R-5b was compatible with a range