Emanuela Libertini

The influence of benzylic protection and allylic substituents on the CuCl-TMEDA catalyzed rearrangement of N-allyl-N-benzyl-2,2-dihaloamides to gamma-lactams. Application to the stereoselective synthesis of pilolactam.

Abstract A number of N-benzylic protecting groups and allylic substituents have been investigated for the rearrangement, promoted by CuCl-TMEDA, of N-allyl-2,2-dihaloamides to 3,4-disubstituted γ-lactams. An appreciable chiral induction was observed at the C-4 site when α-phenylethylamine was used as a chiral protecting group, while an unexpected Diels-Alder reaction occurred when using a 2-furyl-methyl protection. This rearrangement has been applied to the synthesis of pilolactam, a drug with muscarinic activity.

Halogen atom transfer radical addition of α-polychloroesters to olefins promoted by Fe0 filings

Abstract The Kharasch addition of methyl 2,2-dichlorocarboxylates or trichloro acetic acid derivatives to alkenes, affording the corresponding 1:1 adducts, is promoted by the iron filings/N,N-dimethylformamide system.

Synthesis of 5-methoxylated 3-pyrrolin-2-ones via the rearrangement of chlorinated pyrrolidin-2-ones

The reaction of N-substituted 4-methyl-2-pyrrolidinones or 4-diethoxyphosphoryl analogues, carrying at least two chlorine atoms between the C(3) and C(6) carbons, with alkaline methoxide in methanol afforded the corresponding 5-methoxylated 3-pyrrolin-2-ones, useful adducts for the preparation of agrochemicals or medicinal compounds.

1,2-Reduction of α, β-unsaturated hydrazones using dimethylamine-borane/p-toluenesulfonic acid: an easy route to allyl hydrazines

Abstract α,β-Unsaturated hydrazones can be easily converted into N -allyl hydrazines by reaction with dimethylamine–borane/ p -toluenesulfonic acid under mild reaction conditions. The reduction works well for N ′-allylhydrazides but N ′-allyl- N , N -dimethylhydrazines are rapidly reoxidised by air and so need to be manipulated under an inert atmosphere prior to N ′-acylation. Competitive conjugate reduction can also be observed and the regioselectivity of the dimethylamine–borane attack is determined by steric and/or electronic factors. The procedure is also effective for the CN reduction of unconjugated hydrazones.

Unusual access to 5-methoxy or 5,5-dimethoxy-4-methyl-3-pyrrolin-2-ones from chlorinated 4-methyl-pyrrolidin-2-ones

Abstract The reaction of N -substituted 4-methyl-2-pyrrolidinones, carrying not less than two chlorine atoms on the C(3) and C(6) carbons afforded with alkaline methoxide in methanol, under mild conditions, the corresponding 5-methoxy or 5,5-dimethoxy-4-methyl-3-pyrrolin-2-ones in satisfactory yields.

Easy approach to 3-benzylimino-2-pyrrolidinones from 3-chloro-4-chloromethyl-2-pyrrolidinones

Abstract 3-Benzylimino-2-pyrrolidinones can be prepared in good yield by heating 3-chloro-4-chloromethyl-2-pyrrolidinones, benzylamine and NaI in THF at 80°C. An endo -dehydrohalogenation followed by a SN 2 ′ substitution on the intermediate allyl chloride, and finally a shift of the exo -double bond to Δ 3 with attendant tautomerization, appears to be the most probable reaction mechanism.

TELECHELIC OLIGOMERS BY HALOGEN ATOM TRANSFER RADICAL ADDITION

Abstract Monodispersed telechelic oligomers have been efficiently prepared by Fe0−FeCl3 promoted halogen atom transfer radical of functional telogens and taxogens.

2,2-Dichlorination of Aldehydes with the 2,6-Lutidine·HCl/Cl2/CH2Cl2 System: an Environmentally Benign Process Suitable for Scale Up

Abstract An effective and environmentally benign preparation of 2,2-dichloroaldehydes has been achieved by chlorination of aldehydes with Cl 2 (g) in CH 2 Cl 2 , using 2,6-lutidine hydrochloride as recoverable catalyst. Remarkable qualities of the process are: easy work up, high purity products, HCl as the only ‘waste’ stream and inherent bias to the scale up.

Zinc Promoted Addition of Methyl 2,2-Dihalocarboxylates to Carbonyl Compounds

Abstract Methyl 2,2-dihalocarboxylates add easily to carbonyl compounds in fair to good yields through the intermediate formation of 2-haloester enolates; the reaction is promoted by zinc, following a “Barbier” type procedure.

Π-Stacking Signature in NMR Solution Spectra of Thiophene-Based Conjugated Polymers

Studies on conjugated polymers seldom report on their NMR characterization in solution. This paper shows how NMR experiments, both 1H NMR and routine 2D NMR spectra, can help in gaining a further insight into the aggregation behavior of conjugated polymers and could be used to flank the more employed solid-state NMR and other spectroscopy and microscopy techniques in the understanding of the aggregation processes. NMR spectroscopy allows distinguishing, within the class of poorly solvatochromic conjugated polymers, those highly prone to form π-stacked aggregates from the ones that have a low tendency toward π-stacking.