Leucio Rossi

Electrochemical activation of carbon dioxide: Synthesis of organic carbonates

Abstract Electrochemically activated CO2 reacts, under mild conditions, with primary and secondary alcohols bearing a leaving group at the α-position affording the corresponding cyclic carbonates in high yields; unsubstituted alcohols are converted, after addition of EtI, into the corresponding unsymmetrical ethyl carbonates in moderate to good yields. Tertiary alcohols and phenols are stable to the reagent.

The reaction of amines with an electrogenerated base. Improved synthesis of arylcarbamic esters

Abstract The electrogenerated base of 2-pyrrolidone reacts with amines and anilines yielding the corresponding alkyl and aryl carbamates, after addition of carbon dioxide and ethyl iodide. Arylcarbamic esters are obtained in very good yields under mild reaction conditions with respect to the methods so far reported.

The system as mild and safe carboxylating reagent synthesis of organic carbonates

Abstract The system, originating from electrochemical one-electron reduction of dioxygen in dipolar aprotic solvents and in the presence of CO 2 , converts primary and secondary alcohols bearing a leaving group at α orβ position into the corresponding cyclic carbonates in high to excellent yields. Unsubstituted alcohols are also converted, but in unsatisfactory yields, into the corresponding alkyl ethyl carbonates after completion of the reaction by addition of Etl. Tertiary alcohols and phenols are stable to the reagent, thus allowing selective carboxylation of polyhydroxy derivatives. CH-acid containing compounds underfo diferent reactions, if any, with the reagent but in the cases under study the formation of carboxylation products has never been observed.

Enzyme-catalyzed desymmetrization of meso-skipped polyols to useful chiral building blocks

Abstract the biocatalytic desymmetrization, in presence of different enzymes, of two models of polyfunctionalized diols in a meso form was studied PFL was found to be the most selective enzyme with excellent results in chemical and optical yield with some of the tested substrates. The obtained chiral building block was utilized for some useful synthetic transformations toward the synthesis of natural products

Electrogenerated Base-Promoted Synthesis of Organic Carbonates from Alcohols and Carbon Dioxide

Electrogenerated bases promote the reaction between primary alcohols and carbon dioxide to give organic carbonates in excellent yields. Secondary alcohols are converted in moderate yields, whereas tertiary alcohols and phenols are unreactive. 1,2-Diols give a mixture of both cyclic and linear di- and monocarbonates. These latter are intermediates in the reaction pathway leading to the cyclic derivatives.

ENANTIO AND STEREOSELECTIVE SYNTHESIS OF (5R,6S)-6-ACETOXY-HEXADECANOLIDE,A MOSQUITO OVIPOSITION ATTRACTANT PHEROMONE

Abstract The enantio and stereoselective synthesis of (5R, 6S)-6-acetoxy-hexadecanolide is described via chemo, regio and stereoselective opening with LiI of a chiral epoxy alcohol precursor.

New synthesis of oxazolidin-2-ones

Abstract Electrochemically generated tetraethylammonium peroxydicarbonate (TEAPC) and tetraethylammonium carbonate (TEAC) react under very mild conditions, with 1,2-amino alcohols affording, after addition of tosyl chloride, the corresponding oxazolidin-2-ones in fair to good yields.

Boron mediated one-pot aldol-reduction sequence:enantio and diastereoselective synthesis of typical polyketide fragments

Abstract an aldol-reduction one-pot sequence allows syn-syn polyketide fragments such as 7 to be obtained enantio and diastereoselectively. Enol diisopinocampheylborinate is able to influence both the aldol and the subsequent reduction with NaBH4, via a chelate chair like intermediate.

Electrochemical generation of chiral oxazolidin-2-ones anions: a new procedure for the highly diastereoselective conjugate addition to nitroalkenes

Abstract A mild and efficient electrochemical alternative to classical base-catalyzed conjugate addition of nitrogen nucleophiles is reported here. The cleavage of the carbamic NH bond of Evans’ chiral auxiliaries can be very efficiently performed by electrolysis under galvanostatic control and the resulting naked anions used for highly diastereoselective conjugate addition to nitroalkenes. The degree of stereoselectivity was shown to depend on the steric hindrance of the group at the ring C(4) of the starting oxazolidin-2-one.

Ring opening of 2,3-epoxy 1-tosylates to halohydrins and subsequent elaboration to asymmetrical alcohols

Abstract 2,3 -epoxy alcohols-1-tosylates are regio and chemoselectively opened to the corresponding 3-halohydrins (I, Br, Cl): the reduction of the iodohydrins to the monoprotected diols and subsequent standard coupling of the tosyl group leads to a straightforward synthesis of optically active naturally occurring pheromones.