The structure of the unusual anthelmintic pyrrolobenzoxazine terpenoid natural product CJ-12662 was established by X-ray crystallography and partial synthesis from 2-chloronitrobenzene. An unusual Meisenheimer-type rearrangement was used to provide the core pyrrolobenzoxazine heterocycle, and coupling of a tetracyclic pyrrolobenzoxazine lactone with the terpene alcohol was used to complete the synthesis of CJ-12662.

An efficient iterative synthesis of oxazoles involves the cyclization of 2‐alkynyl glycinates (see scheme) formed from the reaction of 1‐alkynyl aluminum reagents with α‐chloroglycinates. This approach was used in the total synthesis of the bisoxazole natural product, (−)‐muscoride A.

At low temperature and in the presence of an acid catalyst, SO 2 adds to 1,3-dienes equilibrating with the corresponding 3,6-dihydro-1,2-oxathiin-2-oxides (sultines). These compounds are unstable above -60°C and equilibrate with the more stable 2,5-dihydrothiophene 1,1-dioxides (sulfolenes). The hetero-Diels-Alder additions of SO 2 are suprafacial and follow the Alder endo rule. The sultines derived from 1-oxy-substituted and 1,3-dioxydisubstituted 1,3-dienes cannot be observed at -100°C but are believed to be formed faster than the corresponding sulfolenes. In the presence of acid catalysts, the 6-oxy-substituted sultines equilibrate with zwitterionic species that react with electron-rich alkenes such as enoxysilanes and allylsilanes, generating β,γ-unsaturated silyl sulfinates that can be desilylated and desulfinylated to generate polypropionate fragments containing up to three contiguous stereogenic centers and an (E)-alkene unit. Alternatively, the silyl sulfinates can be reacted with electrophiles to generate polyfunctional sulfones (one-pot, four-component synthesis of sulfones), or oxidized into sulfonyl chlorides and reacted with amines, then realizing a one-pot, four-component synthesis of polyfunctional sulfonamides. Using enantiomerically enriched dienes such as 1-[(R)-or 1-(S)-phenylethyloxy]-2-methyl-(E,E)-penta-1,3-dien-3-yl isobutyrate, derived from inexpensive (R)-or (S)-1-phenylethanol, enantiomerically enriched stereotriads are obtained in one-pot operations. The latter are ready for further chain elongation. This has permitted the development of expeditious total asymmetric syntheses of important natural products of biological interest such as the baconipyrones, rifamycin S, and apoptolidin A.