Asymmetric Catalysis Route to anti,anti Stereotriads, Illustrated by Applications

Abstract

A short sequence based on asymmetric catalysis, chirality transfer, and an optimized carbometallation protocol gave an anti,anti stereotriad building block in six steps. Both enantiomers of the chirality source, N-methyl ephedrine, are inexpensive, and the auxiliary is recoverable. In one chiral series, the building block was converted to the "B-2" intermediate in Miyashita's synthesis of scytophycin C; in the enantiomeric series, it was converted to a key intermediate for aplyronine A and to the polyketide "cap" for the callipeltins.

Direct Methods for Stereoselective Polypropionate Synthesis: A Survey

“…Parker has also reported the Wittig rearrangement of propargyl ether 165 for the synthesis of anti stereodiad 166, 116 which can be further transformed into (anti,anti)polypropionates (Scheme 37). The highly selective depro- tonation at one of the four allylic positions of 165 is noteworthy.…”

Total Synthesis of (+)-Mupirocin H from d-Glucose

“…As seen in TS-2 , the allylic acetonide protected hydroxyl group of alkene and the boron ligands are in eclipsed form generating steric repulsive strain which is destabilizing this TS making it nonfavored, whereas in TS-1 the allylic acetonide-protected hydroxyl group of alkene and the boron ligands is in noneclipsed form, making this TS more stable and favored, ultimately resulting in the formation of single diastereomer 12 in this reaction. The diastereoselection observed in the Still–Barrish hydroboration is widely documented, and many examples of such hydroboration are reported …”