Diastereoselektive synthese neuartigerMannich-Basen mittels titanderivaten, vorläufige mitteilung

Practical and Robust Method for Regio- and Stereoselective Preparation of (E)-Ketene tert-Butyl TMS Acetals and β-Ketoester-derived tert-Butyl (1Z,3E)-1,3-Bis(TMS)dienol Ethers

We developed an efficient, practical, robust method for the regio- and stereoselective preparation of (E)-ketene trimethylsilyl acetals (KSAs) derived from tert-butyl esters 1. The reaction was performed under convenient reaction conditions; LDA-TMSCl, 0-5 degrees C, and cyclopentyl methyl ether (CPME) solvent. Two kinds of (Z)- and (E)-KSAs derived from alpha-oxygen and alpha-nitrogen-substituted tert-butyl esters, respectively, were also obtained in good yield. The present protocol was successfully applied to a stereocontrolled preparation of useful, but highly reactive (less accessible) beta-ketoester-derived tert-butyl (1Z,3E)-1,3-bis(TMS)dienol ethers 2.

Catalytic Asymmetric Direct Mannich Reactions of Carbonyl Compounds with α-Imino Esters

The development of a direct catalytic asymmetric Mannich reaction is shown and its potential demonstrated by the synthesis of optically active lactones via 4-hydroxyglutamic acid ester derivatives. The catalytic asymmetric Mannich reaction of carbonyl compounds with α-imino esters [Eq. (1); Ts = p-toluenesulfonyl] gives good yields and diastereoselectivities, as well as excellent enantioselectivities.

Lithium Perchlorate Mediated Three Component Reaction for the Preparation of Primary Amines

In the presence of lithium perchlorate in diethyl ether, LPDE, a three-component reaction between aldehydes, sodium hexamethyldisilazane or lithium hexamethyldisilazane, LHMDS, and different nucleophiles proceeds smoothly to afford primary amines in good yields.