Diastereoselective Pinacol Coupling Reactions ofα-Ketoamides Mediated by SmI2: Synthesis of Enantiomerically PureR andS Quaternary Tartaric Acids

Diastereoselective constructions of 1,3-diol units have always been in high demand in synthetic organic chemistry, and preparation of 2-quaternary 1,3-diol units is of major importantance for the synthesis of many biologically significant molecules, such as the Furaquinocins, [1] and chiral ligands. [2] However, the quaternary carbon atom is generally difficult to construct with high diastereoselectivity, because a simple aldol reaction of carbonyl compounds is not efficient in this situation. Several procedures for construction of 2-quaternary 1,3-diol units have already been developed on the basis of the Lewis acid mediated semipinacol rearrangement of a-hydroxy epoxides. However, they generally need one equivalent or an excess of a promoter and produce only the b-sum of the squares of the differences. The rate constants obtained in this way were multiplied by two. [14] Figure 3. a) 1D 1 H-{ 31 P} EXSY NMR spectrum recorded in CDCl 3 at 301 K on a sample containing 1, p-H 2 , and a 100-fold excess of diphenylacetylene. The resonance for 3t was selectively excited and the results for a reaction time of 700 ms are displayed. Exchange into 3b, 9, and cis-stilbene is indicated; b) 2D 1 H-{ 31 P} EXSY spectrum (positive contours) of an identical sample employing a mixing time of 400 ms. Off-diagonal peaks arise due to chemical exchange.

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Samarium-Catalyzed Tandem Semipinacol Rearrangement/Tishchenko Reaction ofα-Hydroxy Epoxides: A Novel Approach to Highly Stereoselective Construction of 2-Quaternary 1,3-Diol Units

Fan

Wang

et al. 2001

Angew. Chem. Int. Ed.

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Diastereoselective Pinacol Coupling Reactions ofα-Ketoamides Mediated by SmI2: Synthesis of Enantiomerically PureR andS Quaternary Tartaric Acids

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Asymmetric synthesis of 1,2-amino alcohols using (S)-indoline chiral auxiliary

Asymmetric synthesis of 1,2-amino alcohols using (S)-indoline chiral auxiliary

Samarium-Catalyzed Tandem Semipinacol Rearrangement/Tishchenko Reaction ofα-Hydroxy Epoxides: A Novel Approach to Highly Stereoselective Construction of 2-Quaternary 1,3-Diol Units

Samarium-Catalyzed Tandem Semipinacol Rearrangement/Tishchenko Reaction ofα-Hydroxy Epoxides: A Novel Approach to Highly Stereoselective Construction of 2-Quaternary 1,3-Diol Units

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