本报告描述了在金鸡纳生物碱胺存在下2-亚烷基苯并[ b ]噻吩酮衍生物与烯酮之间的有机催化级联反应。通过一步合成,制备了包含三个立体中心的螺苯并噻吩苯甲酸环己烷衍生物,其产率为88%至96%,对映选择性(对映体过量(ee))为85至97%,非对映选择性约为14/2/1。因此,该方法为合成新型的光学活性的2-螺苯并噻吩酮提供了有效的途径。
Amidation of α-Amino Acids Using Dichloro(methyl)(3,3,3-trifluoropropyl)silane and Imidazole without Conventional Protection and Deprotection of α-Amino Group
Amidation of amino acids using dichloro(methyl)(3,3,3-trifluoropropyl)silane (MTFPSCl2) and imidazole is described. MTFPSCl2 activates the carboxy group and protects the α-aminogroup of amino acids. The amidation proceeded with 19 amino acids and 19 amines, including α-branched amines and anilines; the corresponding amino acid amides were synthesized in good-to-high yields (up to 96%) with low-to-no
A 1,3,2-dioxathiolane oxide derivative of general formula (I) wherein x represents -S(O)- or -S(O)₂-; R¹ represents hydrogen, alkali metal atom, benzyl or lower alkyl; R² represents lower alkyl which may be substituted by methylthio, or benzyl; and R³ and R⁴ may be the same or different from each other and each represents hydrogen, C₁ to C₁₀ alkyl, guanidyl-substituted lower alkyl, C₃ to C₆ cycloalkyl, phenyl, benzyl or phenoethyl, or R³ and R⁴ are combined together to represent alkylene.
The enantioselective addition of cyanotrimethylsilane (TMSCN) to aldehydes promoted by the addition of a stoichiometric or catalytic amount of organoaluminum complexes of dipeptide esters or alpha-amino acid amides whose amino terminals are modified by a variety of protective groups is described. The reaction of benzaldehyde with TMSCN in the presence of a stoichiometric or catalytic amount of the complex prepared from N-[2-hydroxy-1-naphthyl)methylene]-(S)-valyl-(S)-phenylalanine methyl ester (1a) or N-1(2-hydroxy-1-naphthyl)-methylene]-(S)-valine cyclohexylamide (2a) and trimethylaluminum gives (R)-mandelonitrile in good yield with enantioselectivity as high as 71%. The reaction of cyclohexanecarbaldehyde in the presence of the aluminum complex of N-(1-methyl-2-acetyl-vinyl)-(S)-valine cyclohexylamide (3b) furnishes the corresponding (R)-cyanohydrin in 38% ee, and the reaction of 2,2-dimethylpropionaldehyde with the aluminum complex of N-(4-toluene-sulfonyl)-(S)-valyl-(S)-phenylalanine methyl ester (4a) gives the corresponding (S)-cyanohydrin in 67% ee.
US5214056A
申请人:——
公开号:US5214056A
公开(公告)日:1993-05-25
Access to Spirocyclic Benzothiophenones with Multiple Stereocenters via an Organocatalytic Cascade Reaction
derivatives containing three stereocenters were prepared via one-step synthesis in yields ranging from 88 to 96% and in enantioselectivities (enantiomeric excess (ee)) ranging from 85 to 97%, with diastereoselectivities of approximately 14/2/1. Therefore, this method provides an efficientroute for the synthesis of a new class of opticallyactive 2-spirobenzothiophenones.
本报告描述了在金鸡纳生物碱胺存在下2-亚烷基苯并[ b ]噻吩酮衍生物与烯酮之间的有机催化级联反应。通过一步合成,制备了包含三个立体中心的螺苯并噻吩苯甲酸环己烷衍生物,其产率为88%至96%,对映选择性(对映体过量(ee))为85至97%,非对映选择性约为14/2/1。因此,该方法为合成新型的光学活性的2-螺苯并噻吩酮提供了有效的途径。