Enantioselective Syntheses of Morpholines and Their Homologues via S<sub>N</sub>2-Type Ring Opening of Aziridines and Azetidines with Haloalcohols
作者:Manas K. Ghorai、Dipti Shukla、Kalpataru Das
DOI:10.1021/jo901297d
日期:2009.9.18
yield and enantioselectivity of a variety of substituted nonracemic morpholines and their homologues is described. The reaction proceeds via an SN2-type ring opening of activated aziridines and azetidines by suitable halogenated alcohols in the presence of Lewis acid followed by base-mediated intramolecular ring closure of the resulting haloalkoxy amine.
Practical and Highly Selective Sulfur Ylide-Mediated Asymmetric Epoxidations and Aziridinations Using a Cheap and Readily Available Chiral Sulfide: Extensive Studies To Map Out Scope, Limitations, and Rationalization of Diastereo- and Enantioselectivities
作者:Ona Illa、Mariam Namutebi、Chandreyee Saha、Mehrnoosh Ostovar、C. Chun Chen、Mairi F. Haddow、Sophie Nocquet-Thibault、Matteo Lusi、Eoghan M. McGarrigle、Varinder K. Aggarwal
DOI:10.1021/ja405073w
日期:2013.8.14
The chiral sulfide, isothiocineole, has been synthesized in one step from elemental sulfur, γ-terpinene, and limonene in 61% yield. A mechanism involving radical intermediates for this reaction is proposed based on experimental evidence. The application of isothiocineole to the asymmetric epoxidation of aldehydes and the aziridination of imines is described. Excellent enantioselectivities and diastereoselectivities
Palladium-Mediated Annulation of Vinyl Aziridines with Michael Acceptors: Stereocontrolled Synthesis of Substituted Pyrrolidines and Its Application in a Formal Synthesis of (−)-α-Kainic Acid
作者:Martin A. Lowe、Mehrnoosh Ostovar、Serena Ferrini、C. Chun Chen、Paul G. Lawrence、Francesco Fontana、Andrew A. Calabrese、Varinder K. Aggarwal
DOI:10.1002/anie.201101389
日期:2011.7.4
Just add salt: Vinylaziridines have been treated with methyl vinyl ketone or ethyl thioacrylate in the presence of Pd0 to give pyrrolidines with moderate to good diastereoselectivity. The presence of nBu4NCl was critical to successful annulation. The synthetic utility of the methodology has been demonstrated in a short (formal) synthesis of (−)‐α‐kainic acid.
只需添加盐即可:在Pd 0的存在下,将乙烯基氮丙啶用甲基乙烯基酮或硫代丙烯酸乙酯处理,得到具有中等至良好非对映选择性的吡咯烷。n Bu 4 NCl的存在对于成功的环化至关重要。该方法的综合效用已在(-)-α-海藻酸的简短(正式)合成中得到了证明。
Lewis Acid Catalyzed Highly Stereoselective Domino-Ring-Opening Cyclization of Activated Aziridines with Enolates: Synthesis of Functionalized Chiral γ-Lactams
作者:Manas K. Ghorai、Deo Prakash Tiwari
DOI:10.1021/jo101004x
日期:2010.9.17
A highly enantio- and diastereoselective Lewis acid catalyzed S(N)2-type ring opening followed by cyclization of aziridines with active methylene carbon nucleophiles to functionalized chiral gamma-lactams in a domino fashion has been developed. gamma-Lactams have been desulfonated and decarboxylated, providing pyrrolidone-3-carboxylate and N-tosylpyrrolidinone derivatives, respectively, in good yields.
Stereospecific Ring Expansion of Chiral Vinyl Aziridines
作者:Matthew Brichacek、Mauricio Navarro Villalobos、Alexandra Plichta、Jon T. Njardarson
DOI:10.1021/ol200263g
日期:2011.3.4
In this report, it is demonstrated that chiral vinyl aziridines can be stereospecifically ring expanded. This synthetic approach allows controlled access to chiral 2,5-cis- or 2,5-trans-3-pyrroline products from starting materials with the appropriate aziridine geometry. Twenty three ringexpansion examples, most of which feature a stereospecific cyclization, are presented.