将二乙基硫代二氟甲基膦酸酯加到对映体纯的芳族,杂芳族和脂族醛衍生的亚磺酸亚胺中,得到的N-亚磺酰基α,α-二氟-β-氨基膦酸酯通常具有良好的对映选择性,并且产率很高。与苯乙酮衍生的亚磺胺的反应导致形成具有高非对映选择性且仅中等收率的加成产物。两步脱保护,包括在EtOH中用三氟乙酸处理非对映体纯的N-亚磺酰基α,α-二氟-β-氨基膦酸酯,然后与10 N HCl回流,得到对映体纯的α,α-二氟-β-氨基膦酸酯和α,α-二氟-β-氨基膦酸。(R的N -Cbz导数)-2-氨基-1,1-二氟-2-苯基乙基膦酸酯是制备相应的二氟膦酸酯单酯,二氟膦酸和二氟膦酰胺酸的方便起点。在21°C下,二氟膦酰胺酸在pH高于5的水溶液中稳定。
Convenient Asymmetric Synthesis of β-Substituted α,α-Difluoro-β-amino Acids via Reformatsky Reaction between Davis' <i>N</i>-Sulfinylimines and Ethyl Bromodifluoroacetate
作者:Alexander Sorochinsky、Natalia Voloshin、Andrey Markovsky、Michael Belik、Nobuhiro Yasuda、Hidehiro Uekusa、Taizo Ono、Dmitrii O. Berbasov、Vadim A. Soloshonok
DOI:10.1021/jo030082k
日期:2003.9.1
N-sulfinylimines were found to be efficient as chiral imine equivalents in the high-temperature Reformatsky-type additions with BrZnCF(2)COOEt affording an efficient approach to the enantiomerically pure alpha,alpha-difluoro-beta-amino acids. High chemical and stereochemical yields (drs > 9:1, and as high as 99:1) render this method immediately useful for preparing the target amino acids.
Synthesis of Sulfinimines by Direct Condensation of Sulfinamides with Aldehydes Using Cs<sub>2</sub>CO<sub>3</sub>as an Activating and Dehydrating Reagent
Chiral sulfinimines were prepared from chiral sulfinamides and aldehydes in CH 2 Cl 2 in the presence of cesium carbonate as an amine-activating and dehydrating reagent.
Lewis base-catalyzed diastereoselective Strecker-type reaction between trimethylsilyl cyanide and chiral sulfinimines derived from commercially available (S)-(+)-p-toluenesulfinamide and aliphatic aldehydes proceeded smoothly by using a catalytic amount of tetra-n-butylammonium acetate in DMF to afford the corresponding α-amino nitriles with (Ss,R)-configurations in good to high yields and diastereoselectivities.
Addition of diethyl lithiodifluoromethylphosphonate to enantiopure sulfinimines afforded the corresponding N-sulfinyl alpha,alpha-diffuoro-beta-amino phosphonates with good diastercoselectivity. A two-step deprotection involving treatment of diastereomerically pure N-sulfinyl alpha,alpha-difluoro-beta-amino phosphonates with trifluoroacetic acid in EtOH followed by refluxing with ION HCl afforded enantiopure alpha,alpha-diffuoro-beta-amino phosphonic acids. (C) 2004 Elsevier Ltd. All rights reserved.
Asymmetric Synthesis of Chiral 2-Alkyl-3,3-Dinitro-1-Tosylazetidines
作者:Hui-Seok Yun、Hyo-Jun Lee、Duk-Ho Chang、Su-Jeong Lee、Seung Hee Kim、Jin Seuk Kim、Chang-Woo Cho