Lucilla Favero

Lanthanide(III) trifluoromethanesulfonates as extraordinarily effective new catalysts for the aminolysis of 1,2-epoxides

Abstract Lanthanide(III) trifluoromethanesulfonates (triflates), such as Yb(OTf) 3 , Nd(OTf) 3 and Gd(OTf) 3 , catalyze in a extraordinarily efficient way the aminolysis of 1,2-epoxides, affording the corresponding β-amino alcohols, at room temperature and in a non-protic solvent (CH 2 Cl 2 or toluene), in very good yields. The reactions are completely anti stereoselective and highly regioselective.

Easy direct stereo- and regioselective formation of β-hydroxy nitriles by reaction of 1,2-epoxides with potassium cyanide in the presence of metal salts

Abstract A simple efficient, anti stereoselective, and highly regioselective method for the synthesis of β-hydroxy nitriles by the direct opening of 1,2-epoxides with KCN in acetonitrile, in the presence of metal salts, is described. This new method appears to be competitive with the other methods previously reported.

Dynamics of acetone photodissociation: a surface hopping study

We present on the fly surface hopping simulations of the dynamics of photoexcited acetone in the n → π* band, taking into account both the spin-orbit and the dynamic couplings and allowing for the C-C bond dissociation. The S0, S1, T1 and T2 states were considered and the propagation time was 50 ps. According to the simulation results, after excitation to S1 both Internal Conversion (IC) to S0 and InterSystem Crossing (ISC) to T1 or T2 take place at comparable rates; T2 plays an important role and the simultaneous treatment of the spin-orbit and dynamic couplings is shown to be mandatory to describe the photodynamics. We propose a mechanism that explains the observed fast and slow decay rates of the S1 state of acetone.

Synthesis and Ring-Opening Reactions of the Diastereoisomericcis- andtrans-Epoxides Derived from 3-(Benzyloxy)cyclopentene and 2-(Benzyloxy)-2,5-dihydrofuran

The regiochemical outcome of the ring-opening of epoxides bearing remote polar functionalities has been established in the case of carbocyclic (1 and 2) and the corresponding furanosidic (3 and 4) title epoxides. Under standard conditions, the regioisomeric C-1 products are the sole (from trans epoxides 2 and 4) or predominant (from cis epoxides 1 and 3) ring-opening products. However, under chelating conditions, and only in the case of the cis epoxides 1 and 3, a consistent increase in C-2 selectivity is unexpectedly observed.

MILD LIBF4-PROMOTED AMINOLYSIS OF OXETANES

Abstract LiBF 4 in acetonitrile efficiently catalyzes the aminolysis of trimethylene oxide and 2-octyl oxetane under mild conditions (r.t. or 80°C) to give the corresponding γ-amino alcohols in very good yields.

Yttrium triflate-catalyzed addition of lithium enolates to 1,2-epoxides. Efficient synthesis of γ-hydroxy ketones

A simple, efficient method is described for the synthesis of γ-hydroxy ketones by the direct opening of 1,2-epoxides with lithium enolates derived from simple ketones in anhydrous toluene, in the presence of Y(OTf)3.

REGIO- AND STEREOSELECTIVITY IN THE CYCLIZATION OF ENOLATES DERIVED FROM 4,5-, 5,6-, AND 6,7-EPOXY-1-PHENYL-1-ALKANONES. COMPETITION BETWEEN C- AND O- ALKYLATION

Abstract The results obtained in the base-catalyzed intramolecular cyclization of enolates derived from some representative 4,5-, 5,6-, and 6,7-epoxy ketones and of the corresponding alkenes are discussed. The LHMDS/Sc(OTf)3 protocol on epoxy ketones appears to be a valuable tool for the stereoselective obtainment of the corresponding cyclic γ-hydroxy ketones (γ-HKs).

Regiochemical control of the ring opening of 1,2-epoxides by means of chelating processes. Part 17: Synthesis and opening reactions of cis- and trans-oxides derived from (2S,6R)-2-benzyloxy-6-methyl-3,6-dihydro-2H-pyran, (2R,6R)- and (2S,6R)-2-methoxy-6-methyl-5,6-dihydro-2H-pyran

Abstract The regiochemical behavior of the title deoxy anhydrosugars, prepared in an enantioselective way starting from methyl α- d -glucopyranoside, was examined in opening reactions, both under standard and chelating conditions. The results clearly indicate the influence of the reaction conditions and the importance of the relative orientation of the methyl group with respect to the oxirane ring on the regiochemical outcome of these epoxides. An useful inversion of regioselectivity is obtained in some cases.

Regiochemical control of the ring opening of 1,2-Epoxides by means of chelating processes. 11. Ring opening reactions of aliphatic mono- and difunctionalized cis and trans 2,3- and 3,4-Epoxy Esters

Abstract The regiochemical outcome of the ring opening of 1,2-epoxides through chelation processes assisted by metal ions, was verified in the azidolysis of simple aliphatic cis and trans 2,3- and 3,4-epoxy esters and in the corresponding derivatives bearing an ether functionality (OBn) in an allylic relationship to the oxirane ring. The results indicate that the behavior of these epoxides is influenced both by the opening conditions (standard or metal-assisted) and the promoting metal salt [LiClO4 or Mg(ClO4)2].

Regiochemical Control of the Ring Opening of 1,2-Epoxides by Means of Chelating Processes. Part 14: Regioselectivity of the Opening Reactions with MeOH of Remote O-Substituted 1,2-Epoxycyclohexanes under Gas-Phase Operating Conditions.

Abstract The regiochemical behavior of cyclohexene oxides bearing a remote O -functionality was determined in the gas-phase in opening reactions with MeOH, using a gaseous acid (D 3 + , C n H 5 + , Me 2 F + ) as the promoting agent. The results obtained indicate the incursion in the opening process in the gas phase of H + (or D + )-mediated chelated bidentate species completely absent in the corresponding reactions (methanolysis) carried out in the condensed phase.