Total Synthesis of (+)-Lycoricidine and Conduramine B-1, ent-C-1, C-4, D-1, ent-F-1, and ent-F-4, and Formal Synthesis of (-)-Laminitol: a C2-Symmetric Chiral-Pool-Based Flexible Strategy.

A facile and diversity-oriented synthetic strategy toward aminocyclitol natural products from inexpensive C2-symmetric l-tartaric acid was developed. The pivotal epoxide was used as a common intermediate to accomplish eight diverse target molecules in six to eleven steps. Various allyl-amine-type conduramines were synthesized in a diastereoselective manner. Heck arylation was explored to construct a phenanthridone ring in a concise synthesis of (+)-lycoricidine. In addition, a highly efficient formal synthesis of (-)-laminitol was developed.

Chiral pool based efficient synthesis of the aminocyclitol core and furanoside of (-)-hygromycin A: formal total synthesis of (-)-hygromycin A.

A chiral pool based synthetic strategy that leads from the readily available and inexpensive C(2)-symmetric tartaric acids to the chiral O-isopropylidenebenzooxazole--a convenient precursor to the aminocyclitol core of hygromycin A as well as the chiral γ-disilyloxybutyrolactone--a pivotal intermediate to approach to the furanoside of hygromycin A.

A flexible strategy based on a C2-symmetric pool of chiral substrates: concise synthesis of (+)-valienamine, key intermediate of (+)- pancratistatin, and conduramines A-1 and E.

A new strategy invoking a new application of the [3,3] sigmatropic rearrangement of allylic azides and the presence of a C(2) symmetry element within a pool of chiral substrates was evolved. Not only does this simple flexible strategy provide a concise approach to (+)-valienamine, but it also can readily be adopted for the synthesis of conduramines A-1 and E and the enantiopure azido carbonate 4, a key intermediate of (+)-pancratistatin.

Asymmetric [3,3]- and [1,3]-sigmatropic rearrangements of gamma-allyloxy vinylogous urethanes.

Vinylogous urethanes derived from condensation of prolinol or prolinol tert-butyldimethylsilyl ether with 4-allyloxyketoester were found to undergo a thermal [3,3]-sigmatropic rearrangement, providing compounds with N-substituted quaternary carbon centers. Cyclizations (subsequently or in situ) of the rearranged products generated hexahydro-3,4-dioxa-8a-aza-as-indacen-2-ones. Various terminally substituted allyloxy ketoesters and arylmethoxy ketoesters were found to generate tricyclic compounds via [1,3]-sigmatropic rearrangement. Finally, tricyclic lactones were transformed successfully into lactams.