Cyclodimerization of Alkynes with Phosphine-Free Ruthenium Carbene Complexes: Carbene Consumption by a Shunted Alkyne Oligomerization
作者:Steven T. Diver、Amol A. Kulkarni、Daniel A. Clark、Brian P. Peppers
DOI:10.1021/ja0705689
日期:2007.5.1
A new cyclodimerization of ruthenium carbenes and alkynes is reported. The cyclodimerization produces substituted cyclopentadienes and consumes the carbene complex. Cyclodimerization of alkynes is predominant at low alkene concentrations and was found to be competitive with enyne metathesis. The presence of the ortho alkyl ether in the ruthenium carbene complex appears to be a critical determinant
Tandem dienyne cross-metathesis/ring-closing metathesis
作者:Jason A Smulik、Steven T Diver
DOI:10.1016/s0040-4039(00)01922-5
日期:2001.1
Tandem enyne cross-metathesis/ring-closing metathesis between terminal alkynes and 1,5-hexadiene has been demonstrated using the 1,3-dimesityl-4,5-dihydroimidazol-2-ylidene-substituted ruthenium benzylidene complex. Synthesis of 2-substituted 1,3-cyclohexadienes using this one step tandem reaction is reported. In addition, metathesis products were subjected to [4+2] cycloaddition with N-methylmaleimide
Ring Synthesis by Stereoselective, Methylene-Free Enyne Cross Metathesis
作者:Amol A. Kulkarni、Steven T. Diver
DOI:10.1021/ja0476922
日期:2004.7.1
Tandem enyne metathesis between 1-alkynes and 1,5-cyclooctadiene or all-cis-1,4-polybutadiene resulted in a direct, one-step ring synthesis of cyclohexadienes by methylene-free metathesis. The use of methylene-free metathesis conditions provided apparent Z-selectivity in the intermolecular enyne metathesis step.
Synthesis of 1,3-cyclohexadienes by tandem diene–alkyne metathesis: improved procedure
作者:Mark D. Middleton、Steven T. Diver
DOI:10.1016/j.tetlet.2005.04.017
日期:2005.6
A practical synthesis of 2-substituted 1,3-cyclohexadienes by the cross enyne metathesis between alkynes and 1,5-hexadiene is reported. The isolation of the 1,3-cyclohexadienes has been hampered by the formation of an inseparable triene by-product. The use of a second consecutive cross alkene metathesis to give water-soluble products allowed removal of this by-product. Using this one-pot procedure, a synthesis of cyclohexadienes from simple starting materials was developed. The procedure was used in a three-step synthesis of a functionalized tetrahydroquinoline using Pd(II)-catalyzed chloroacetoxyiation (Backvall reaction) for cyclohexadiene functionalization. (c) 2005 Elsevier Ltd. All rights reserved.