Isothiourea-Catalyzed Enantioselective Carboxy Group Transfer
作者:Caroline Joannesse、Craig P. Johnston、Carmen Concellón、Carmen Simal、Douglas Philp、Andrew D. Smith
DOI:10.1002/anie.200904333
日期:2009.11.9
Transferable skills: Enantiomerically pure isothioureas promote the O‐ to C‐carboxyl grouptransfer of oxazolyl carbonates with excellent levels of enantiocontrol (see scheme). The origin of the enantioselectivity of this process was probed mechanistically and rationalized computationally.
Isothiourea-Mediated Asymmetric O- to C-Carboxyl Transfer of Oxazolyl Carbonates: Structure-Selectivity Profiles and Mechanistic Studies
作者:Caroline Joannesse、Craig P. Johnston、Louis C. Morrill、Philip A. Woods、Madeleine Kieffer、Tobias A. Nigst、Herbert Mayr、Tomas Lebl、Douglas Philp、Ryan A. Bragg、Andrew D. Smith
DOI:10.1002/chem.201102847
日期:2012.2.20
The structural motif within a series of tetrahydropyrimidine‐based isothioureas necessary for generating high asymmetric induction in the asymmetric Steglich rearrangement of oxazolylcarbonates is fully explored, with crossover and dynamic 19F NMR experiments used to develop a mechanistic understanding of this transformation.
充分探索了一系列四氢嘧啶基异硫脲中的结构基序,这些结构对于恶唑碳酸酯的不对称Steglich重排产生高不对称诱导是必要的,并使用交叉和动态19 F NMR实验来发展对该转变的机理理解。
Catalytic enantioselective Steglich rearrangements using chiral N-heterocyclic carbenes
作者:Craig D. Campbell、Carmen Concellón、Andrew D. Smith
DOI:10.1016/j.tetasy.2011.04.001
日期:2011.4
The evaluation of a range of enantiomerically pure NHCs, prepared in situ from imidazolinium or triazolium salt precatalysts, to promote the catalytic enantioselective Steglich rearrangement of oxazolyl carbonates to their C-carboxyazlactones, is reported. Modest levels of enantioselectivity (up to 66% ee) are observed using oxazolidinone derived NHCs. (C) 2011 Elsevier Ltd. All rights reserved.
Enantiodivergent Steglich rearrangement of O-carboxylazlactones catalyzed by a chirality switchable helicene containing a 4-aminopyridine unit
A pseudo-enantiomeric pair of optically switchable helicenes containing a catalytic 4-N-methylaminopyridine (MAP) bottom unit and a C2-symmetric, (10R,11R)-dimethoxymethyl-dibenzosuberane top template was synthesized. They underwent complementary photoswitching at 290 nm (P/M′, <1/>99) and 340 nm (P/M′, 91/9) and unidirectional thermo-rotation at 130 °C (P/M′, >99/<1). They were utilized to catalyze
合成了含有催化的4- N-甲基氨基吡啶(MAP)底部单元和C 2对称(10 R,11 R)-二甲氧基甲基-二苯并亚戊烷顶部模板的可光学转换的螺旋对映体的对映体对映体。他们在290 nm(P / M ',<1 /> 99)和340 nm(P / M ',91/9)处进行互补光开关,并在130°C(P / M ',> 99 / <1)。它们被用来催化O-对C的对映异构Steglich重排。-羧基内酯,形成两种对映体,分别具有高达91%ee(R)和94%ee(S)的对映体。