Free‐radical addition of acyl radicals to chiral aza‐Baylis–Hillmanadducts was shown to afford the corresponding 1,4‐amino ketones in good yields and good 1,2‐stereocontrol. These ketones were then elaborated further using conditions varying as a function of the nature of the N‐protecting group. Robust N–Ts protection thus allowed the formation, under acidic conditions, of a cyclic iminium which was
1,3,5-Triaza-7-phosphaadamantane (PTA): A Practical and Versatile Nucleophilic Phosphine Organocatalyst
作者:Xiaofang Tang、Bo Zhang、Zhengrong He、Ruili Gao、Zhengjie He
DOI:10.1002/adsc.200700071
日期:2007.8.6
cycloaddition reaction of 4-substituted 2,3-butadienoates with N-tosylimines, PTA is also proven to be a comparable catalyst as tributylphosphine (PBu3). By systematic comparison with other structurally similar N,P catalysts, it is concluded that the superiority of PTA in the above nucleophilic catalysis is attributable to its comparable nucleophilicity with that of trialkylphosphines. The feasibility
amount of DBU in DCM, N-p-toluenesulphonyl carbamates 6a–c, prepared starting from the corresponding Baylis–Hillman adducts, gave (E)-2-(p-toluenesulphonylaminomethyl)propenoates 3a–c, exclusively. On the contrary, changing DABCO for DBU, 2-methylene-3-p-toluenesulfonylamino esters 4a–f were obtained in good yield starting from N-p-toluenesulphonyl carbamates 6a–f. In analogy, N-acyl carbamates 9a–f were
Frustrated Lewis Pair (FLP)-Catalyzed Hydrogenation of Aza-Morita–Baylis–Hillman Adducts and Sequential Organo-FLP Catalysis
作者:Imtiaz Khan、Mattia Manzotti、Graham J. Tizzard、Simon J. Coles、Rebecca L. Melen、Louis C. Morrill
DOI:10.1021/acscatal.7b03077
日期:2017.11.3
Herein we report the metal-free diastereoselective frustratedLewis pair (FLP)-catalyzed hydrogenation of aza-Morita–Baylis–Hillman (aza-MBH) adducts, accessing a diverse range of stereodefined β-amino acid derivatives in excellent isolated yields (28 examples, 89% average yield, up to 90:10 d.r.). Furthermore, sequential organo-FLP catalysis has been developed. An initial organocatalyzed aza-MBH reaction
A Simple, Mild Synthesis of 3-Aryl-2-methylidene-3-(p-tolylsulfonylamino)propanoates
作者:EM Campi、A Holmes、P Perlmutter、CC Teo
DOI:10.1071/ch9951535
日期:——
A mild synthesis of 3-aryl-2-methylidene-3-( tosylamino ) propanoates is described. The potential utility of these products is demonstrated by a simple preparation of the ethyl esters of syn- and anti-3-amino-2-methyl-3-phenylpropanoic acid.