Reduction of Ketones with Triisobutylaluminum. The Stereochemistry of Reduction of 3,3,5-Trimethylcyclohexanone

Investigation of the Stereoselective Synthesis of the Indane Dimer PH46A, a New Potential Anti-inflammatory Agent

“…Both the mechanism of reduction (a 6-membered cyclic transition state, involving ketone coordination to aluminum) and the steric demands using TiBA are very similar to the MPVO reaction. , The key differences are that TiBA reduction is essentially irreversible and that no ketone byproduct is formed, features which we expected would help overcome the low conversions observed with Al­(O i Pr) 3 reductions at practical concentrations. However, the reduction product (the aluminate formed from the alkoxide after ketone reduction) can itself undergo equilibration via a MPVO-type mechanism if unreacted ketone is also present . When applied to our system, essentially complete conversion and a promising D1/D2 ratio (8:92) were achieved (Table , entry 8A), also supporting our hypothesis that diastereoisomer D2 is the kinetic product with reductions which proceed through a MPVO-type transition state.…”

“…However, the reduction product (the aluminate formed from the alkoxide after ketone reduction) can itself undergo equilibration via a MPVO-type mechanism if unreacted ketone is also present. 16 When applied to our system, essentially complete conversion and a promising D1/D2 ratio (8:92) were achieved ( Table 4 , entry 8A), also supporting our hypothesis that diastereoisomer D2 is the kinetic product with reductions which proceed through a MPVO-type transition state. Based on the apparent efficiency and clean HPLC profile of this reaction, this route was explored further ( Table 4 , entries 8B–D).…”

An Alumino‐Mannich Reaction of Organoaluminum Reagents, Silylated Amines, and Aldehydes

“…The use of alkylaluminums is also possible, generating the product amines in moderate to good yields (Table , 7 d – 7 j ). These results are in stark contrast to the lack of reactivity observed for alkylboron reagents [C(sp 3 )‐based nucleophiles] in the Petasis borono‐Mannich reaction …”

Absolute Configuration of cis- and trans-2-(o-Bromophenyl)cyclohexanols and (+)-cis-2-(o-Bromophenyl)cyclohexylamine

“…and Mislow (7). 8 Determination of the conformation and relative configuration of cis-and trans-2-arylcyclohexanols by NMR was discussed by Huitric et al H-2 at 6 3.33 for the tosylate VIII. The width of about 25 Hz.…”