Optically Pure Dihydroxy γ-Alkylated γ-Butyrolactones Starting from l-Tartaric Acid: Application to Formal and Total Syntheses of Natural Products

Highly stereocontrolled and regiocontrolled syntheses of 2,3,4-trisubstituted alkanoates and lactones

New chlorodiols (±)-3 and (±)-5 are densely functionalized and versatile synthons. They are converted in one step on a gram scale into 2-chlorolactones (±)-6 and (±)-7 and into 4-hydroxy glycidate esters (±)-9 and (±)-10. The 4-hydroxy glycidate esters (±)-9 and (±)-10 are converted stereospecifically and regiospecifically into oxazolines (±)-13 and (±)-14 and into cyclic carbamates (±)-18-(±)-20. The 4-hydroxy glycidate ester (±)-10 undergoes stereocontrolled and regiocontrolled epoxide opening by sodium azide to form the 2-azido-3,4-dihydroxy alkanoate (±)-21. Finally, chlorodiol (±)-5 reacts stereospecifically with silver triflate to form the 2,3-dihydroxyfuranone (±)-26.

(2R,3S)-2-Benzyl-3-(2,3,4,6-tetra-O-acetyl-β-d-glucopyranos-yloxy)butanolide

The title compound, C₂₅H₃₀O₁₂, which demonstrates a significant hepatoprotective effect, has comparable geometrical parameters to those of similar compounds. The absolute configuration of the title compound, viz. 2R,3S, was identified from the Flack parameter of 0.05 (17) and the Hooft parameter of 0.04 (6).

Synthesis and olefination of carbonyl compounds using solid-supported reagents

The development and application of three new solid-supported reagents for use in the synthesis or olefination of carbonyl compounds are described. The reagents include the Weinreb amide, Mukaiyama's S-2-pyridyl thioate and a Peterson methylenation reagent. As solid-supports p-benzyl alcohol resin, Wang resin and Merrifield resin (1-2% crosslinked polystyrene) have been used.

Highly Stereoselective Aldol Reaction for the Synthesis of γ-Lactones Starting from Tartaric Acid

A simple stereoselective process for the synthesis of highly substituted gamma-lactones was developed based on aldol reactions between the enolate of dioxanes derived from tartaric acid and aldehydes. A range of aromatic and aliphatic aldehydes were reacted, in most cases achieving good yields and stereoselectivity. The limitations of this reaction were identified and a transition state is proposed.