Alberto Rodríguez-Vicente

NEW INTRAMOLECULAR CYCLIZATION AND REARRANGEMENT PROCESSES BASED ON THE RADICAL ARYL-ARYL COUPLING OF ARYLSUBSTITUTED 2-AZETIDINONES

Abstract New polycyclic 2-azetidinones having fused or not biaryl units are easily prepared by the tin-mediated, intramolecular aryl-aryl radical cyclization of readily available arylsubstituted 2-azetidinones. The regioselectivity and efficiency of the process is determined both by the length of the linking chain through the β-lactam nucleus and by the number and position of the substituents on the aromatic acceptor ring.

A convenient trans-stereoselective synthesis of phenanthridine derived 2-azetidinones using the Staudinger ketene-imine cycloaddition

Staudinger reactions between acid chlorides having electron-withdrawing substituents at the α-position and phenanthridine, provide new fused tetracyclic 2-azetidinones in good yields with exclusive trans-stereoselectivity, both in racemic and enantiopure forms.

A New Radical Route to C4-Unsubstituted β-Lactams

Abstract C4-Unsubstituted β-lactams 3 are conveniently prepared from easily available 4-formyl-β-lactams 1, in a sequential three step synthesis, using as the key step a radical reductive decarbonylation of 4-carboxy derivatives through their phenyl selenoesters 2.

Functionalized eight-membered lactams via [3,3] sigmatropic rearrangement of 2-azetidinone-tethered 1,5-dienes

Abstract The thermally induced [3,3] sigmatropic (Cope) rearrangement of cis-β-lactams 1 having alkenyl groups at both the C3 and C4 positions to yield new functionalized eight-membered lactams (tetrahydroazocinones) 2 , in racemic as well as optically pure forms, is reported. This process involves a novel, concerted C3 C4 bond breakage of the β-lactam nucleus helped by ring strain.

The asymmetric synthesis of 2,3-benzocarbapenems by intramolecular aryl radical cyclizations

Abstract Racemic and enantiomerically pure 2,3-benzocarbapenems 1 are obtained in good yields by the tin-mediated, intramolecular aryl radical cyclizations of the readily available 4-alkenyl- N -(2-halogenophenyl)-β-lactams 2 .

Lewis Acid-Assisted Ene Cyclization of 2-Azetidinone-Tethered Enals: Synthesis of Enantiopure Carbacepham Derivatives

Diastereocontrolled Lewis acid-catalyzed preparation of enantiopure carbacepham derivatives have been developed starting from 2-azetidinone-tethered enals. The BF3.Et2O-promoted reaction of alkenylaldehydes 1 and 16 is effective as carbocyclization protocol to afford 4-substituted 5-hydroxycarbacephams or 3-substituted 4,5-dihydroxycarbacephams, respectively, by a type I carbonyl-ene reaction, while the BF3.Et2O or SnCl4-mediated type II carbonyl-ene cyclization of alkenylaldehydes 2 furnishes 3-methylene 5-hydroxycarbacephams along with the corresponding 3-halo 5-hydroxycarbacepham. The stereochemical outcome of these carbonyl-ene cyclizations leading to carbacepham derivatives can be explained in terms of six-membered, cyclic chair-like transition-state models. The formation of halocarbacepham derivatives is proposed to proceed by a stepwise mechanism.

The asymmetric synthesis of novel tin-functionalized carbapenam systems through radical cyclization of enyne β-lactams

Abstract New chiral, non-racemic, vinylstannyl carbapenams 2 are easily accessible by the regio- and stereocontrolled tin-mediated, vinyl radical intramolecular cyclization of enyne β-lactams 1 .

The use of aqueous dimethylamine as reagent for the regiospecific C4-epimerization of cis-3-substituted 4-formyl-2-azetidinones

Abstract A simple and efficient method for the synthesis of trans -3-substituted 4-formyl-2-azetidinones 2 is described based on the regiospecific C 4-epimerization of the cis -isomers 1 using aqueous dimethylamine as reagent in heterogeneous medium.