Exposure of a mixture of propargyl vinyl ketone and a nucleophilic primary or secondary amine to activated dry silica gel in the absence of solvent leads to a cascade of reactions that results in the formation of an aminocyclopentenone. The reaction with triethylamine leads to a cross-conjugated cyclopentadienone.
Tandem alkylation–cyclization process via an O,C-dianion
摘要:
A general protocol for preparing densely functionalized cyclopentenones through a tandem nucleophilic addition-deprotonation-alkylation-cyclization process is described. Addition of lithioallene 2 to enamides 1 generates tetrahedral intermediate 3. Deprotonation of the gamma carbon atom of the allene function in situ, followed by trapping by a suitable electrophile and cyclization during workup leads to C6 substituted cyclopentenones 6. (c) 2005 Elsevier Ltd. All rights reserved.
作者:Francis Dhoro、Tor E. Kristensen、Vegar Stockmann、Glenn P. A. Yap、Marcus A. Tius
DOI:10.1021/ja0718873
日期:2007.6.13
The chiral auxiliary directed addition of a propargyllithium reagent to a morpholino enamide, followed by exposure of the adduct to activated dry Florisil in the absence of solvent and in the presence of a primary or secondary amine, leads to a cascade of reactions that results in the formation of an aminocyclopentenone as a single diastereoisomer. The reaction can also be conducted intramolecularly.
作者:Paul E. Harrington、Tsuyoshi Murai、Chester Chu、Marcus A. Tius
DOI:10.1021/ja020591o
日期:2002.8.1
The scope of an enantioselective cyclopentannelation reaction that makes use of allenyl ether-derived nucleophiles has been probed. The enantioselectivity is induced by a traceless chiral auxiliary that is easily derived from camphor. It has been shown that for gamma-substituted allene ethers that are axially chiral, very high enantiomeric excesses of cyclopentenone products are observed in the matched cases. Two fundamentally different mechanisms are observed, one for the cyclizations of allenyl ketones (see eq 7), the other for the cyclizations of allenyl alcohols (see eq 11). The methodology is versatile, efficient, and well-suited for applications in synthesis.
Tandem alkylation–cyclization process via an O,C-dianion
作者:April R. Banaag、Gideon O. Berger、Francis Dhoro、Derrick B. delos Santos、Darryl D. Dixon、James P. Mitchell、Bradley K. Tokeshi、Marcus A. Tius
DOI:10.1016/j.tet.2005.01.097
日期:2005.3
A general protocol for preparing densely functionalized cyclopentenones through a tandem nucleophilic addition-deprotonation-alkylation-cyclization process is described. Addition of lithioallene 2 to enamides 1 generates tetrahedral intermediate 3. Deprotonation of the gamma carbon atom of the allene function in situ, followed by trapping by a suitable electrophile and cyclization during workup leads to C6 substituted cyclopentenones 6. (c) 2005 Elsevier Ltd. All rights reserved.
Interrupted Nazarov Cyclization on Silica Gel
作者:Francis Dhoro、Marcus A. Tius
DOI:10.1021/ja053393g
日期:2005.9.1
Exposure of a mixture of propargyl vinyl ketone and a nucleophilic primary or secondary amine to activated dry silica gel in the absence of solvent leads to a cascade of reactions that results in the formation of an aminocyclopentenone. The reaction with triethylamine leads to a cross-conjugated cyclopentadienone.