C-2/C-3 Annulation and C-2 Alkylation of Indoles with 2-Alkoxycyclopropanoate Esters
作者:Barbora Bajtos、Ming Yu、Hongda Zhao、Brian L. Pagenkopf
DOI:10.1021/ja067821+
日期:2007.8.1
reaction between various indoles and 2-alkoxycyclopropanoate esters is reported. Both high efficiency and complete stereochemical control were observed in some cases with this annulation process. A single stereocenter on the cyclopropane controls the diastereoselective formation of up to four new stereocenters. A different reaction course was observed with 3-substitutedindole substrates, and an intervening
A Powerful New Strategy for Diversity-Oriented Synthesis of Pyrroles from Donor−Acceptor Cyclopropanes and Nitriles
作者:Ming Yu、Brian L. Pagenkopf
DOI:10.1021/ol036180+
日期:2003.12.1
Lewisacid activated donor-acceptor cyclopropanes react with aliphatic, aromatic, and alpha,beta-unsaturated nitriles in a novel cascade [3 + 2] dipolarcycloaddition, dehydration, and tautomerization sequence to afford pyrroles in moderate to excellent overall yield. This cost-effective and regiospecific method is ideally suited for the preparation of combinatorial libraries. [reaction: see text]
Synthesis of 2,2‘-Bipyrroles and 2,2‘-Thienylpyrroles from Donor−Acceptor Cyclopropanes and 2-Cyanoheteroles
作者:Ming Yu、G. Dan Pantos、Jonathan L. Sessler、Brian L. Pagenkopf
DOI:10.1021/ol049857h
日期:2004.3.1
[reaction: see text] Two new series of 2,2'-bipyrroles and 2,2'-thienylpyrroles have been prepared by trimethylsilyl trifluoromethanesulfonate (TMSOTf)-mediated reaction of donor-acceptor cyclopropanes with 2-cyanopyrroles and 2-cyanothiophene, respectively. This method opens the door toward a wide variety of unsymmetrical bipyrroles and thienylpyrroles.
Synthesis of Indolizines and Benzoindolizines by Annulation of Donor-Acceptor Cyclopropanes with Electron-Deficient Pyridines and Quinolines
作者:Nicholas A. Morra、Christian L. Morales、Barbora Bajtos、Xin Wang、Hyosook Jang、Jian Wang、Ming Yu、Brian L. Pagenkopf
DOI:10.1002/adsc.200600298
日期:2006.11
The formal [3+2] dipolar cycloaddition (or annulation) of donor-acceptor cyclopropanoate esters with pyridines and 5-nitroquinoline is reported. Electron-deficientpyridine dipolarophiles (R=CN, CO2Et, COMe) participate in the annulation whereas electron rich species do not. The product 2,3-dihydroindolizines undergo rapid autooxidation, and the X-ray structures for two of the aromatic products are
Mechanism of the <i>N</i>-Cyclopropylimine-1-pyrroline Photorearrangement
作者:Diego Sampedro、Alberto Soldevilla、Miguel A. Rodríguez、Pedro J. Campos、Massimo Olivucci
DOI:10.1021/ja0467566
日期:2005.1.1
We present here a combined experimental and computational investigation into the photorearrangement of N-cyclopropylimines to yield pyrrolines. We show that the photochemistry, regiochemistry, and stereochemistry of the reaction can be understood in terms of a mechanism involving barrierless evolution in three different (S(2), S(1), S(0)) singlet states and sequential decay through two different (S(2)/S(1)