Hui-Jun Chen

Expeditious entry to the chamigrane endoperoxide family of natural products.

Several members of the recently reported peroxy chamigrane family of natural products were synthesized via a distereoselective route with a novel facial-selective epoxidation of a spiroundecadiene, a facile epoxide rearrangement, and a Co(II)-mediated silylperoxidation as the key steps. Adaptation of the diastereoselective route to an enantioselective one is also illustrated.

A Novel Allyl Transfer Coupled with a Grob Fragmentation.

A novel acid-promoted rearrangement is disclosed. In the previously unknown transformation, an allyl group migrated to an in situ formed carbocation stabilized by an electron-rich aryl or heteroaryl group, resulting in a stereoselective intramolecular Grob fragmentation. The outcome of the rearrangement observed with an array of substrates can be satisfactorily rationalized using a working hypothesis with the aid of a six-membered transition state similar to those proposed for the anionic oxy-Cope or oxonia-Cope rearrangements, but involving only one instead of two double bonds.

Synthesis and absolute configuration of hylodiglyceride isolated from Hylodendron gabunensis

A recently isolated bismonoglyceride of heptadecanedioic acid, which represents a novel type of natural monoglycerides (i.e., with two instead of only one glycerol unit in the molecular architecture), was synthesized in enantiopure forms using a chiral-pool based approach with the 17-carbon chain constructed from undec-10-enoic acid and oct-7-en-1-ol via a cross metathesis and the stereogenic centers derived from (R)-(2,2-dimethyl-1,3-dioxolan-4-yl)methanol. An analogue with a longer alkyl chain was also synthesized. The synthetic samples not only allowed for establishment of the absolute configuration but also helped to reveal some minor yet unignorable errors in the H-1 NMR data for the natural product. Optical rotation and NMR data acquired in DMSO and DMSO-d(6), respectively, are also presented