Zoltan G. Hajos

Total synthesis of optically active (−)17β-hydroxy-Δ9(10)-desA-androsten-5-one

Abstract (±)7,7a-Dihydro-1β-hydroxy-7aβ-methyl-5(6H)-indanone was resolved via the hydrogen phthalate-brucine salt. The dextrorotatory enantiomer (+)4 was then converted in a 5-step stereospecific total synthesis to the important BCD tricyclic intermediate (−)13. The synthesis also adds additional proof for the absolute configuration of the bicyclic keto alcohol (+)4 by correlation with (±_13, a known degradation product of natural steroids.

Preparation of positive inotropes using glycidyl derivatives: Influence of metal ions and solvent on stereochemical outcome

Abstract The choice of base and solvent has a dramatic effect on the attack of nitrogen nucleophiles on enantiomerically enriched glycidyl sulfonates 8. Under the proper conditions attack can be largely limited to displacement of the sulfonate moiety thus retaining the original stereochemistry. Conditions were also noted where the initial attack resulted from epoxide opening. Subsequent attack of the intermediate alkoxide on the sulfonate group then yielded a product of opposite stereochemistry. The methodology was applied to the syntheses of both enantiomers of a new selective, positive ionotropic agent, 1 (carsatrin), 4-[bis(4-fluorophenyl)methyl]-(α-[9H-purin-6-ylthio)methyl]-1-piperazineethanol.

Novel Synthesis of Ethynyl Vinyl Carbinols and 2,5-Disubstituted Furans from Aldehydes

Abstract Gem-substituted aryl, aralkenyl and 2-furyl ethynyl vinyi carbinols as well as 2,5-disubstituted furans can be obtained by a novel addition and rearrangement reaction of acetylene with the appropriate aldehydes.

Proline-catalysed asymmetric ketol cyclizations: The template mechanism revisited

A modified template mechanism based on modelling studies of energy minimised complexes is presented for the asymmetric proline-catalysed cyclization of triketones1,2 and3 to the 2S,3S-ketols1a,2a and3a respectively. The template model involves a three-point contact as favoured in enzyme-substrate interactions. Our minimisation studies are in agreement with the divergent behaviour of the 6,5-, 6,6-and 6,7-bicyclic systems. They support the high 93.4%ee observed with the 6,5-bicyclic ketol and the lower 73%ee found with the 6,6-bicyclic ketol. The calculations also explain the lack of asymmetric induction with the 6,7-bicyclic system