A versatile route for the stereoselective synthesis of oxybiotin

Metal free synthesis of 2,3-dideoxy-α, β-unsaturated carbohydrate enals (Perlin aldehydes)

A metal free synthesis of enantiopure 2,3-dideoxy-α, β-unsaturated carbohydrate enals (Perlin aldehydes), in CH₃CN-0.02 N H₂SO₄ in water (1:1, v/v) with 0.5 equivalent additives (4-hydroxy-6-methyl-2-pyrone or 4-amino coumarin), has been reported. This efficient protocol works well for the acetylated glycals (glucal, galactal and arabinal) and afforded Perlin aldehydes and hemiacetals in acceptable to good yields. Whereas, benzylated glycals furnished respective Perlin aldehydes, hemiacetals and the 2-deoxy derivatives, under similar reaction conditions. The products yields were significantly reduced when the additives were removed from the reaction mixture, indicating that they constitute an essential component of this approach. Further the use of 0.02 N H₂SO₄ in water: acetonitrile (1:1, v/v) solvent system is essential for the formation of Perlin aldehydes. The similar reactions under neutral reaction conditions (CH₃CN:H₂O, 1:1, v/v) with additives, afforded the hemiacetals as major product. This methodology is a metal free approach to Perlin aldehyde synthesis and therefore having additional benefit of its use in preparation of bioactive drug molecules, where metal toxicity is the major concern.

Formal synthesis of cis-solamin: acid-catalyzed one-step construction of 2,5-disubstituted tetrahydrofuran

A divergent strategy has been used for the concise and efficient enantioselective formal synthesis of Annonaceous acetogenin cis-solamin. Our synthetic strategy comprises concise preparation of the diepoxyester via an 11-membered silaketal constructed by ring-closing metathesis after the dimerization of chiral epoxides, and uses an acid-catalyzed tandem intramolecular SN2-like reaction to construct the threo-cis-threo configuration of the tetrahydrofuran-diol moiety.

The evolution of comprehensive strategies for furanoid glycal synthesis and their applications

Cyclic enol ether frameworks, especially stereochemically pure furanoid and pyranoid glycals are well known highly functionalized chiral building blocks.

‘Chiron’ approach to stereoselective synthesis of sphinganine and unnatural safingol, an antineoplastic and antipsoriatic agent

Highly stereoselective total syntheses of sphinganine 1 and antineoplastic and antipsoriatic drug safingol 17 have been demonstrated.

Glycal approach to the synthesis of macrolide (−)-A26771B

A convergent synthesis of macrolide natural product (−)-A26771B starting from d-glucal is reported. Key features of this synthesis involve Ferrier rearrangement, cross metathesis of chiral fragments 3 and 4 and Yamaguchi macrolactonization.

Substrate and stereocontrolled iodocycloetherification of highly functionalized enantiomerically pure allylic alcohols: application to synthesis of cytotoxic 2-epi jaspine B and its biological evaluation

A mechanistic study on iodocycloetherification of enantiopure allylic alcohols is established. Its application to synthesis of marine cytotoxic 2-epi jaspine B has been demonstrated.

A new approach to asymmetric synthesis of infectocaryone

A new approach to the asymmetric synthesis of infectocaryone featuring a regioselective and stereoselective Diels–Alder reaction of an isomeric dienophile mixture is developed.

A short enantioselective synthesis of 3-epi-jaspine B and (+)-oxybiotin via an intramolecular tandem desilylation oxa-Michael addition strategy

A new synthesis of cytotoxic 3-epi-jaspine B (34.7% overall yield; 97% ee) and (+)-oxybiotin (21.2% overall yield; 97% ee) is described starting from cis-2-butene-1,4-diol. The key reactions employed in the synthesis are Sharpless asymmetric epoxidation and a novel tandem desilylation-oxa Michael addition reaction.

A chiron approach to aminocytitols by Petasis-Borono-Mannich reaction: formal synthesis of (+)-conduramine E and (-)-conduramine E

A chiron approach to a stereoselective route for the synthesis of aminocytitols from carbohydrates is described. The formal synthesis of (+)-conduramine E and (-)-conduramine E was achieved by utilizing this strategy. The key features of the synthetic strategy include one-pot three-component Petasis-Borono-Mannich reaction to introduce the syn-β-amino alcohol functionality of conduramine E and ring-closing metathesis to construct its carbocyclic core. The present synthetic approach paves the way for stereoselective synthesis of several conduramines starting from carbohydrates.