A series of enantiomerically enriched tropanes was synthesized by the rhodium(II) octanoatecatalyzed reaction of various N-BOC-protected pyrroles with vinyldiazomethanes. The overall 3 + 4 annulation occurs by a tandem cyclopropanation/Cope rearrangement. Asymmetric induction was best achieved in these transformations by using either (S)-lactate or (R)-pantolactone as a chiral auxiliary on the vinyldiazomethanes. Reactions carried out with the chiral catalyst tetrakis-[N-(4-tert-butylbenzenesulfonyl)-(L)-prolinato]dirhodium (2) provided moderate asymmetric induction, but also resulted in the formation of isomeric azabicyclooctane side products. The utility of the synthetic process was demonstrated through the asymmetric synthesis of (-)-anhydroecgonine methyl ester and (-)-ferruginine.

Two 3,3‘-dialkyl-5,5‘,6,6‘-tetramethyl-1,1‘-biphenyl-2,2‘-diols (where alkyl = t-Bu, adamantyl) were prepared in two steps and resolved as the menthol phosphate derivative. Addition of the dipotassium salt of each biphenolate to various Mo(N-Aryl)(CHR)(OTf)2(DME) complexes produced racemic and enantiopure compounds of the type Mo(N-aryl)(CHR)(biphenolate). X-ray crystallographic studies of syn-Mo(N-2,6-i-Pr2C6H3)(CHCMe2Ph)[(S)-Biphen] and syn-Mo(N-2-CF3C6H4)(CHCMe3)[(S)-Biad](pyridine) proved the absolute stereochemistry of the biphenolate ligands. Neophylidene and neopentylidene complexes were found to have predominantly the syn conformation in solution. The [syn]/[anti] equilibrium constant for Mo(N-Aryl)(CHR)[Biphen] complexes increased in magnitude with decreasing size of the arylimido ligand, and decreased upon reducing the steric bulk of the alkylidene substituent. The rates of exchange of syn and anti isomers, as determined by single-parameter line shape analysis and by spin saturation transfer, were found to be on the order of ∼1 s-1 at 22 °C.

Decomposition of vinyldiazoacetates by rhodium(II) (N-dodecylbenzenesulfonyl)prolinate (Rh2(S-DOSP)4, 1) in the presence of dienes results in a direct and highly enantioselective method for the formation of cis-divinylcyclopropanes. Combination of this process with a subsequent Cope rearrangement results in a highly enantioselective synthesis of a variety of cycloheptadienes containing multiple stereogenic centers.