Gerard Ple

Polyunsaturated aldehydes by direct polyvinylogation of carbonyl compounds using functionalized phosphonates

Carbonyl compounds are converted into polyethylenic aldehydes in a one pot reaction with the anions of phosphonates 1. followed by a mild acidic hydrolysis.

Functionalized vinylic organolithium compounds, synthetic equivalent of ω-lithio sorbaldehyde

Functional vinylic anions 2 and 3 react with aldehydes and ketones leading after hydrolysis to polyenic aldehydes 7. They have been used for the synthesis of navenone B 8.

Handy access to chiral N,N′-disubstituted 3-aminopyrrolidines.

Abstract A new and rapid synthesis of (S)-3-aminopyrrolidines 7 is proposed from N-protected (S)-Asparagine. Basic cyclization of methyl N-Z-(S)-Asparaginate 1 followed by one-pot N-benzylation directly leads to (S)-aminosuccinimide 3 which, after cleavage of the Z-protecting group, is converted to corresponding imines and readily reduced to disubstituted chiral 3-aminopyrrolidines 7 . Almost no racemization (≤5%) of the original amino-acid asymmetric center may be observed.

Axial and helical chirality of some spiro-1,3-dioxanes

The diastereoisomerism of some spiro 1,3-dioxanes with axial chirality and of some trispiro derivatives exhibiting an axial and a hitherto unreported helical chirality for spiranic compounds is discussed.

Terminally substituted linear conjugated polyenes: Precursors of molecular wires.

Abstract As precursors of molecular wires, linear conjugated polyenes with protected hydroquinone terminal groups 1a–c have been obtained from gentisic aldehyde by condensation with 1-ethoxy-6-lithiohexa-1,3,5-triene 6, followed by reacting the resultant aldehydes 5 with the dianion of the bis-phosphonate 7.

Synthesis of Dienals by Condensation of Carbonyl Compounds with a New Reagent, the 4-Lithio-1-trimethylsiloxybutadiene

Abstract Carbonyl compounds 2 are converted into conjugated dienals 3. in a one pot reaction, by a condensation with lithio-4 trimethylsiloxybutadiene, followed by a mild acidic hydrolysis.

A novel synthesis of AZT

Abstract A novel synthesis of AZT has been achieved from two commercial available products acetaldehyde and d -mannitol. The originality of the synthesis consists of using the powerful monovinylogation reagent, the 2-lithio-1-trimethylsiloxyethylene, and to introduce the thymine moiety and to build the furanose ring in the same and last step.

Synthesis and stereochemistry of some dispiro-1,3-dioxanes with axial and helical chirality

Abstract The stereoisomerism of some dispiro-1,3-dioxanes is discussed in terms of conformational analysis and axial and helical chirality. The influence of the flexibility of the rings on the representative number of isomers and on their NMR spectra is commented. For the 3,12-disubstituted-1,5,10,14-teraoxadispiro[5.2.5.2]hexadecane derivatives displaying a semiflexible structure two configurational diastereomers named “6,9-dispiro-syn” and “6,9-dispiro-anti” were identified. The ratio between these isomers was determined by the diastereotopicity of protons and carbon atoms.

Conformational analysis of some spiro and polyspiro 1,3-dioxane compounds with axial and helical chirality

Some spire and trispiro 1,3-dioxane compounds are discussed in terms of their axial and the helical chirality (all rings are six-membered). The influence of conformation on the number of isomers and on their interrelationship has been followed by means of high resolution and dynamic NMR experiments using the diastereotopicity of the proton and carbon atoms. Interconversions between configurational isomers (presenting three chiral elements) without the breaking of bonds are reported.

Synthesis and Stereochemistry of Some 1,3-Oxazolidine Systems Based on TRIS (α,α,α-trimethylolaminomethane) and Related Aminopolyols Skeleton. Part 2: 1-Aza-3,7-dioxabicyclo[3.3.0]octanes

The reaction of TRIS with equivalent amounts of two carbonyl compounds is shown to afford, diastereoselectively, the title compounds. The results are discussed as a synthetic strategy and the stereochemistry is supported by theoretical calculations and high resolution NMR data.