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.
Synthesis of Isothiocineole and Application in Multigram-Scale Sulfur Ylide Mediated Asymmetric Epoxidation and Aziridination
作者:Eoghan McGarrigle、Varinder Aggarwal、Martin Fearraigh、Johnathan Matlock、Ona Illa
DOI:10.1055/s-0037-1609580
日期:2018.9
ylide-mediated asymmetricepoxidation of aldehydes and the asymmetric aziridination of imines on a >5 g scale is demonstrated. The synthesis of the chiral sulfide isothiocineole from limonene and elemental sulfur on multi-gram scale and its alkylation to make >50 g of the corresponding benzylsulfonium salt are described. The application of this salt to the sulfur ylide-mediated asymmetricepoxidation of aldehydes
diastereoselective and enantioselective formal [4+1] ylide annulation of chiral sulfonium salts with various substituted α-substituted nitroalkene leading to opticallyactive isoxazoline N-oxides using CF3SO3− as a key anion has been explored. The salient features of this methodology include high diastereo- and enantioselecties, easily available starting materials, mild reaction conditions, simple procedure
已经探索了使用CF 3 SO 3 -作为关键阴离子的手性锍盐与各种取代的α-取代硝基烯烃的非对映选择性和对映选择性形式[4+1]叶立德环化产生光学活性异恶唑啉N-氧化物。该方法的显着特点包括高非对映选择性和对映选择性、易于获得的起始材料、温和的反应条件、简单的程序、广泛的底物范围以及异恶唑啉N-氧化物可方便地转化为其他功能化化合物。
A mild access to chiral syn 1,2-diaryl glycols by stereoselective ring opening of ortho substituted trans 2,3-diaryl-oxiranes using Amberlyst 15 in H2O/THF system
Amberlyst 15 was an efficient and green catalyst for the reaction of 2,3-diaryloxiranes with H2O in organic co-solvent to prepare glycols in high yield. Ortho substituted trans 2,3-diaryloxiranes afforded the corresponding syn glycols stereo- and enantiospecifically. Stereoselectivity appeared related to the coordination ability of the substituents, irrespective of their electronic properties. Indeed o-OCH3 and o-OBn substituted syn glycols were obtained in high stereochemical ratios (6/1 and 10/1, respectively), and o-OTIPS and o-NO2 substituted ones were obtained as exclusive products, with the same ee of the parent epoxides. (C) 2015 Elsevier Ltd. All rights reserved.