Pd(0) or Pd(II)-catalyzed ring-opening reactions of benzylidene- and alkylidenecyclopropyl ketones and aldehydes
摘要:
Pd(0) catalyzed reactions of methylenecyclopropyl carbonyl compounds afforded a convenient method for the synthesis of conjugate (E,E)-1,3-diene derivatives 2 in good to excellent yields. Moreover, we also found that Pd(II)-catalyzed reactions of methylenecyclopropyl carbonyl compounds with water gave 1,5-diketones in good to high yields via a carbene-palladium intermediate. The plausible reaction mechanisms have also been provided on the basis of control and O-18-labeling experiments. (c) 2009 Elsevier Ltd. All rights reserved.
HOTf-Catalyzed Rearrangement of Methylenecyclopropane Aryl and Alkyl Alcohols
作者:Xiang-Ying Tang、Min Shi
DOI:10.1002/ejoc.201000509
日期:2010.7
An efficient method to synthesize multisubstituted naphthalene and cyclobutanol derivatives through ring opening/ring enlargement of readily available methylenecyclopropane diaryl alcohols or dialkyl- and monoalkyl- as well as monoaryl alcohols in moderate to good yields has been described in this paper. The formation of naphthalene derivatives is a sequential reaction involving a cation-induced ring
Palladium(II) and palladium(0)-cocatalyzed ring opening and oxidation reactions of 2-(arylmethylene)cyclopropylcarbinols
作者:Min Shi、Guo-Qiang Tian、Jia Li
DOI:10.1016/j.tet.2009.02.028
日期:2009.4
In the presence of Pd(II) acetate and triethylamine as well as triphenylphosphine, 2-(arylmethylene)cyclopropylcarbinols 1 underwent ringopening and oxidation reactions smoothly to deliver (2E,4E)-5-arylpenta-2,4-dienals 2 in toluene at 60 °C in moderate to good yields under ambient atmosphere. Mechanisms involved with an in situ generated Pd(0) species from Pd(II) and Et3N or PPh3 catalyzed isomerization
Palladium-Catalyzed Reactions of 3-Substituted Methylenecyclopropanes
作者:Li-Xiong Shao、Jia Li、Bao-Yu Wang、Min Shi
DOI:10.1002/ejoc.201001082
日期:2010.11
Pd-catalyzed reactions of 3-substitutedmethylenecyclopropanes (MCPs), in which the substituents can be either hydroxymethyl or formyl, have been thoroughly investigated in the presence or absence of an acid source. It was found that the Pd-catalyzed reactions of methylenecyclopropylcarbinols (Z)-1 in the presence of acetic acid, acetic acid 2-methylene-but-3-enyl esters 4 can be formed in moderate
Ring-Opening Reaction of Methylenecyclopropanes Derived from Methylenecyclopropyl Aldehydes through Cope Rearrangement
作者:Xiang-Ying Tang、Yin Wei、Min Shi
DOI:10.1002/ejoc.201000880
日期:2010.11
Tandem Wittig reaction/Cope rearrangement of methylenecyclopropyl aldehydes 1 with cinnamyltriphenylphosphonium bromide afforded a convenient method for the synthesis of cyclopentene derivatives 2 in moderate yields in a one-pot manner. Dialkyl 2-[(2-methylenecyclopropyl)methylene]malonates 3 derived from methylenecyclopropyl aldehydes 1 could produce two kinds of cyclopentene derivatives, 4 and 5
Organo-Selenium Induced Radical Ring-Opening Intramolecular Cyclization or Electrophilic Cyclization of 2- (Arylmethylene)cyclopropylaldehyde: A Tunable Synthesis of 1-Naphthaldehydes or 3-Oxabicyclo[3.1.0]hexan-2-ols
作者:Maozhong Miao、Xian Huang
DOI:10.1021/jo900805a
日期:2009.8.7
1-Naphthaldehydes and 3-oxabicyclo[3.1.0]hexan-2-ols can be prepared, respectively, by the intramolecular alkylation and cyclization of (E)-2-(arylmethylene)cyclopropylaldehyde 1 mediated by different organo-selenium reagents. The properties of selenium reagents may play an important role in the reactions. A rationale for these transformations is proposed.