Francesco Manescalchi

Inversion of configuration of alcohols through nucleophilic displacement promoted by nitrate ions.

Abstract Inversion of configuration of hydroxy functionalities in biologically significant structures has been performed under mild conditions through nucleophilic displacement by nitrate ion.

Reductive amination of 1,4- and 1,5-dicarbonyl compounds with (S)-valine methyl ester. Synthesis of (S)-2-phenylpyrrolidine and (S)-2-phenylpiperidine

Abstract The reductive amination of 4-phenyl-4-oxobutanal and 5-phenyl-5-oxopentanal with (S)-valine methyl ester and sodium cyanoborohydride afforded the N-substituted (S)-2-phenylpyrrolidine (88% d.e.) and (S)-2-phenylpiperidine (96% d.e.), from which the levorotatory NH cyclic amines were obtained. On the other hand, the analogous reductive amination of simple ketones, 2,5 hexanedione, and 2,6-heptanedione was poorly selective.

Diastereoselective synthesis of 2,5-dimethylpyrrolidines and 2,6-dimethylpiperidines by reductive amination of 2,5-hexanedione and 2,6-heptanedione with hydride reagents

Abstract The reductive amination of 2,5-hexanedione and 2,6-heptanedione with ammonia and primary amines in the presence of hydride regents afforded 2,5-dimethylpyrrolidines and 2,6-dimethylpiperidines with variable diastercoselectivity, as the cis/trans ratio was affected by the size of the ring formed and the steric and electronic properties of the nitrogen substituent. Increasing the bulkiness of the nitrogen substituent, the cis pyrrolidines and the trans -piperidines were obtained with enhanced selectivity.

Chemistry of alkali metal tetracarbonylferrates. Reduction of acid chlorides to aldehydes by A polymer-supported iron carbonyl complex

Abstract The polymer-supported HFe(CO) 4 − anion can be easily prepared from potassium tetracarbonylhydridoferrate by an ion-exchange process with the chloride form of the anion-exchange resin Amberlyst A-26. This polymeric reagent, which can be readily dehydrated by washing with anhydrous solvents, reduces acid chlorides to the corresponding aldehydes under mild conditions.

Polymer-supported phosphonates. Olefins from aldehydes, ketones, and dioxolans by means of polymer-supported phosphonates

Phosphonates substituted with electron-withdrawing groups (CN and CO2Me) have been supported, by means of a neutralization reaction, on the macroreticular anion-exchange resin Amberlyst A-26. Treatment of carbonyl compounds with the polymer-bound phosphonate in various solvents gave olefins in high yields, at room temperature. Either batch or column techniques are employed, the latter offering the opportunity of a continuous procedure. The simultaneous use of the phosphonate resin and of an acidic one (Amberlyst 15 H) allowed the direct sequential hydrolysis and olefination of dioxolans.

Chlorination of organic compounds by means of polymer-supported chlorine

Chlorination of organic compounds is achieved, under mild conditions, using chlorine incorporated into an anion exchange resin.

Polymer-supported reagents: polar effects in substrate selectivity

A remarkable selectivity effect has been observed in the competitive reaction of a polymer-supported nucleophile with pairs of halides of analogous size and different polarity.