Jean-Baptiste Verlhac

Organotin homoenolate equivalents - access to β-acyl-and β-aryl-propionaldehydes through heterosubstituted allyltins and vinyltins

Abstract Although, α-ethoxycrotyltributyltin can be used as an equivalent of the homoenolate anion CH3-CHCH2CHO in reaction with acyl chlorides, the non-substituted α-ethoxyallyltributyltin could not be employed in this way. γ-Methoxyvinyltins, easily prepared by hydrostannation of propargylic ethers, are successfully employed as synthetic equivalents of the homoenolate anions-CH2CH2CHO and -CH2CH2COCH3 in reactions with acyl chlorides. A silylated γ-methoxyvinyltin, which is both a vinyltin and an allylsilane, reacts with acyl chlorides and aryl bromides as a promising equivalent of the homoenolate anion -CH2CH2CHO and tolerates a wide range of other reactive functional groups.

Préparation d'aminométhyltributylétains par stannylation de sels d'immonium au moyen du chlorure de tributylstannylmagnésium. Applications à la synthèse de β-aminoalcools

Abstract Tributylstannylmagnesium chloride reacts with immonium salts and gives non-substituted, α-substituted or α,α-disubstituted aminomethyltributyltins. The reaction, which can be extended to stannylation by tributylstannylalkalis, is not affected by the nature of the anionic part of the immonium salt. Transmetallation of aminomethyltributyltins with butyllithium, followed by condensation with carbonyl compounds, provides a regiospecific route to β-aminoalcohols.

Alkane hydroxylation reactions catalysed by binuclear manganese and iron complexes

Abstract Binuclear manganese( III IV ) or iron( III III ) complexes efficiently functionalize cyclohexane using hydroperoxides or peracids as oxidants. A mechanistic study clearly demonstrate the role of dioxygen gas in these hydroxylation reactions. Moreover, it was demonstrated that the cleavage of the peroxy bond occurred mainly by homolysis.

A new carboxylic acid with branched ponytails for the solubilization of Mn(II) and Co(II) ions in perfluorocarbons

Abstract The synthesis of a carboxylic acid (C8F17(CH2)3)2CHCOOH 3 bearing two long branched perfluoroalkyl-alkyl chains is described. This acid is highly soluble in perfluorocarbons and is a useful ligand for the preparation of transition metal complexes that are soluble in fluorinated media. This is illustrated by the preparation of the manganese(II)- and cobalt(II)-carboxylate complexes, both of which are soluble in perfluorocarbons and are thus potentially interesting starting materials for metal-catalyzed reactions under fluorous biphasic procedures.

Synthesis of di-µ-oxo manganese(III/IV) complexes as functional models of L. Plantarum pseudo-catalase: influence of electronic and steric factors; catalysis and kinetics of hydrogen peroxide disproportionation

Di-µ-oxo dimanganese(III/IV) complexes are efficient catalysts for H2O2 disproportionation in neutral aqueous medium; the activity can be correlated to the electron density on the metal and the accessibility of the catalytic site.

Alkane hydroxylation by a manganese analogue of the iron core from methane monooxygenase

A binuclear manganese (II/II) complex with a µ-hydroxo bridging ligand catalyses the hydroxylation of cyclohexane in the presence of tart-butyl hydroperoxide (TBHP).

Synthesis of acylsilanes via transmetalation of 1-triorganosilyloxyvinyltin derivatives

Abstract Transmetalation of 1-triorganosilyloxyvinyltin derivatives occurs with a reverse Brook rearrangement. Subsequent trapping with various electrophiles affords new acylsilanes.

New copper(I) and iron(II) complexes for atom transfer radical macrocyclisation reactions

New Cu(I) and Fe(II) complexes have been synthesized and proved to be efficient catalysts for atom transfer radical addition (ATRA) reactions. The catalytic activity was found to be greater than existing atom transfer systems based upon CuCl(bipyridine) or RuCl2(PPh3)3, for example. The addition of a reducing agent considerably improved the efficiency of the usual procedures.

Atom transfer radical cyclisations of activated and unactivated N-allylhaloacetamides and N-homoallylhaloacetamides using chiral and non-chiral copper complexes

Activated N-tosyl-2,2,2-trichloroacetamide 6a, N-benzyl-2,2,2-trichloroacetamide 6d, 2,2-dichloroacetamides 6b–c and 6e–f and 2-monohaloacetamides 11a–g undergo efficient 5-exo atom transfer radical cyclisations at room temperature mediated by CuCl or CuBr in the presence of tris(N,N-dimethylaminoethylene)amine 3 (trien-Me6). The efficiency and stereoselectivity of these cyclisations was found to be greater than existing published atom transfer procedures based upon CuCl(bipyridine), RuCl2(PPh3)3 and CuCl(TMEDA)2. The product distribution for the cyclisation onto alkyne 11g was found to be solvent dependent. Attempts to make larger ring sizes by endo cyclisation of N-tosylacetamides 19a–c led to a competing 5-exoipso aromatic substitution into the N-tosyl group followed by re-aromatisation and loss of SO2 to furnish an amidyl radical. Cyclisation of N-homoallylacetamides 25a–d proceeded smoothly to give δ-lactams with a range of catalysts based upon ligands 2 and 26. The stereoselectivity of cyclisation to give γ lactams could be somewhat influenced by using chiral enantiopure copper complexes 28–30 suggesting that the reactions may involve metal-complexed radicals.

Synthesis of porphyrins with pendant arms: Participation of the ancillary ligands to the complexation process in proteic medium

Abstract Ortho substituted porphyrins are able to complex copper (+II) in a neutral aqueous medium containing an excess of bovine albumine.