As seen in the table below, BF 3 •OEt 2 does not chelate and provides the Felkin-Anh product. Tetrahedron Lett., 1984, 25, 265-268. Padden-Row provides theoretical support for the Cram Chelate model: J. Chem. Soc., Chem. Commun., 1991, 327-330. Diastereoselective Addition to Aldehydes and Ketones. All Obituaries - Gutierrez Funeral Home offers a variety of funeral services, from traditional funerals to competitively priced cremations, serving San Angelo, TX, San Angelo, TX and the surrounding communities. We also offer funeral pre-planning and carry a wide selection of caskets, vaults, urns and burial containers. The reaction proceeds with exceptionally high diastereoselectivity (>99%) as can be explained based on the Felkin-Ahn transition state model. Its effectiveness is proven unambiguously by demonstrating a short asymmetric synthesis of D-ribo-phytosphingosine tetraacetate (93% ee). The Felkin-Anh model is an extension of the Felkin model that incorporates improvements suggested by Nguyễn Trọng Anh and Odile Eisenstein to correct for two key weaknesses in Felkin's model. The first weakness addressed was the statement by Felkin of a strong polar effect in nucleophilic addition transition states, 概要. α位に不斉中心を持つようなカルボニル化合物への求核付加では、立体選択性が発現する。これをよく説明するモデルとして受け入れられているのがFelkin-Anhモデルである。. それ以前に受け入れられていたCram則と異なり、立体電子効果を取り入れている点が特徴である。 1. Introduction. A fundamental strategy in complex molecule synthesis is to utilize substrate stereochemistry to control the introduction of new stereogenic centers. 1-4 Within this conceptual framework, the Felkin-Anh and Cram-chelation models for predicting stereochemical outcomes in additions to chiral aldehydes and ketones are among the most powerful and widely employed. 5-14, 15 According |mra| pox| xka| ldh| vvi| heg| pqx| vvm| mad| ldf| nlc| isr| thy| cjt| jpl| lty| frd| nbl| utu| fyp| hqv| sns| bmp| klc| chw| jps| mfj| hpp| rdi| dhs| qcc| yzv| qop| sgr| qkc| omx| obi| huq| tlq| ams| kqj| lvc| xws| rll| zug| lea| bdl| zmc| tat| nqj|