L-Ascorbic acid serves as chiral starting material for the cycloaddition reaction, leading to the heterocyclic core unit of (+)-prosophylline. Stereoselective hydrogenation and synthesis of (+)-desoxoprosophylline. The synthetic pathway includes the formation of an O-protected 5-azido-2,3-chain elongation yields the desired alkaloid. dideoxysugar which is subjected to a tandem Wittig [2+3]-2,3,6-Substituted chiral piperidine alkaloids such as (Ο©)-sures that our reaction sequence for the (Ο©)-enantiomer of desoxprosophylline and its derivatives also offers the pos-prosopine ( 1), (Ο©)-prosopinine ( 2), (Β±)-prosophylline (3), and micropine (4) can be isolated from various Prosopis sibility of synthesizing their optical antipodes.
The general strategy of the synthesis is outlined in species [1] or, in the case of micropine from Microcos philippinensis. [2] These compounds have recently been targets of Scheme 1. The heterocyclic ring system should be accessible by a tandem Wittig [2Ο©3]-cycloaddition, a reaction se-increasing interest for total synthesis. Some 6-alkyl-3hydroxy-2-(hydroxymethyl)piperidines have been synthe-quence previously used by us in the synthesis of chiral, nonracemic piperidine derivatives. [8] The introduction of the sized in racemic form, [3] but during the last few years a growing number of enantioselective syntheses of Prosopis [4] side chain should be accomplished by standard procedures published by Cook, Beholz, and Stille. [3d,3e] and Microcos alkaloids [5] and their derivatives have been published.