Highly stereoselective synthesis of a seven-membered carbasugar via triisobutylaluminium promoted Claisen rearrangement

Synthesis of novel seven-membered carbasugars and evaluation of their glycosidase inhibition potentials

Here, we report the synthesis of five novel seven-membered carbasugar analogs. We adopted a chiral-pool strategy starting from the cheap and readily available d-mannitol to synthesize these ring-expanded carbasugars. Apart from several regioselective protecting group manipulations, these syntheses involved Wittig olefination and ring-closing metathesis as the key steps. We observed an unprecedented deoxygenation reaction of an allylic benzyl ether upon treatment with H₂/Pd during the synthesis. Preliminary biological evaluation of the carbasugars revealed that these ring expanded carbasugars act as inhibitors of various glycosidases. This study highlights the importance of the synthesis of novel ring expanded carbasugars and their biological exploration.

Here, we report the synthesis of five novel seven-membered carbasugar analogs.

Synthesis of (±)-Sundiversifolide Based on Lewis Acid-Mediated Claisen Rearrangement

A new and concise synthesis of (+/-)-sundiversifolide (1), an allelopathic bisnor-sesquiterpene lactone isolated from germinating sunflower (Helianthus annuus L.) seeds, was achieved by employing Lewis acid-mediated Claisen rearrangement as the key step.

Synthesis of the AB subunit of angelmicin B through a tandem alkoxy radical fragmentation-etherification sequence

The synthesis of the tricyclic enone 2, corresponding to the AB subunit of the novel tyrosine kinase inhibitor angelmicin B, is described. The strategy centers on an intramolecular Diels-Alder (IMDA) reaction on triene 4 to provide the complex decalin 3, which is elaborated to 2. Other key steps are the formation of the THF ring in 2 through a tandem alkoxy radical fragmentation-etherification on the lactol derived from 3, and the synthesis of 4 via a ring-closing ene-yne metathesis (RCEYM).

From Common Carbohydrates to Enantiopure Cyclooctane Polyols and Glycomimetics via Deoxygenative Zirconocene Ring Contraction

D-Arabinose and D-glucose are transformed into the identical vinyl furanoside, whose role is to serve as the precursor to enantiopure cyclooctadienone 6. The key steps of this relay involve a zirconocene-promoted ring contraction and [3,3] sigmatropic rearrangement of an enynol. Subsequently defined are convenient synthetic routes to several cyclooctane-1,2,3-triols, 1,2,3,4,5-pentaols, and structurally related glycomimetics.