alpha-Linolenic acid (ALA), eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) have been subjected to esterification with ethanol in presence of lipase B from Candida antarctica (Novozym 435®), in solvent free condition. The use of alcohol donors triethyl orthoformate (TEOF) or diethyl carbonate (DEC) instead of free ethanol, allowed working in irreversible esterification conditions and ALA-, EPA- and DHA-ethyl esters were obtained in quantitative yields.

Dimethyl carbonate was used as alcohol donor in the esterification of naproxen in the presence of immobilised lipase B from Candida antarctica (Novozym 435). The conjugation of hydrolysis of dimethyl carbonate and esterification of acid, created irreversible operative conditions so permitting the recovery of S-naproxen in high ee (>98%). The adopted procedure has a general use.

The effects of the presence of a molecular monolayer on the dilatational properties of the air/water interface have been investigated. Two water insoluble amphiphiles, dipalmitoyl phosphatidyl choline and quercetin 3-O-palmitate, were spread onto a pendant drop and the dynamic surface pressure was measured by means of drop shape analysis. The surface dilatational elasticity and viscosity of the spread monolayers were also determined by the oscillating drop technique. Constraints on the range of measuring conditions were investigated and we demonstrated that the pressure-area isotherms derived from oscillatory dynamic measurements display phase behaviour similar to that found in equilibrium measurements, albeit at reduced resolution. Both the amphiphiles formed purely elastic films that were characterised by a dilatational modulus that depended on the surface concentration and obeyed a power scaling law. The exponent of the relationship could be related to the thermodynamic conditions prevailing at the interface. The phospholipid monolayer scaling exponent was 2.8 in a temperature range of 20-26 degrees C indicates a favourable solvency of molecules in the bidimensional matrix. A very high scaling exponent (11.8 at 7 degrees C) for quercetin palmitate was interpreted assuming that molecules self-organise in fibre-like structures. This interface structure and the phase behaviour was found consistent with observations of the surface film obtained by Brewster angle microscopy. The structured quercetin 3-O-palmitate monolayers are disrupted by temperature increase or by adding a 0.2 molar fraction of the immiscible dipalmitoyl phosphatidyl choline.

Lipase from Candida antarctica has been successfully used to realise the selective esterification of the four 1-(1-hydroxyethyl)-3-ethylferrocene isomers, possessing central/planar chirality. In this reaction, the lipase recognises only the two isomers possessing an (R)-configuration, independently from planar chirality. This allows us to split the mixture into two couples of diastereoisomers, namely the (Sp,Rc)-/(Rp,Rc)- and (Rp,Sc)-/(Sp,Sc)-isomers, conveniently separated in the single constituents by crystallisation from hexane.

Lipases are useful catalysts to realise in non-conventional medium esterifications and alcoholysis of polyhydroxylated compounds with high level of regioselectivity. This paper describes some examples of regioprotection–deprotection of flavonoids and conduritols, realised in our laboratory, using Pseudomonas cepacia, Mucor miehei and Candida cylindracea (C. rugosa) lipases.

Racemic 2-hydroxymethyl-1-iodoferrocene (±)-1 was subjected to esterification in the presence of lipase from Candida antarctica (Novozym® 435) to afford (1S,2S)-2-acetoxymethyl-1-iodoferrocene (−)-2 having 89% ee and unreacted (1R,2R)-2-hydroxymethyl-1-iodoferrocene (+)-1 in enantiopure form. A single enantiomer of 2-hydroxymethyl-1-iodoferrocene gave easy access to new ferrocenes and biferrocenes possessing only planar chirality.

Racemic 2-hydroxymethyl-1-phenylthioferrocene 5 and 2-hydroxymethyl-1-tert-butylthioferrocene 6 were subjected to kinetic resolution via acetylation catalysed by lipase from Candida antarctica (Novozym® 435) or Mucor miehei (Lipozyme® IM). The obtained enantiopure thioethers underwent chemical oxygenation at the sulfur atom to give the corresponding ferrocenyl sulfoxides with settled central/planar chirality.

Both enantiomers of 2-hydroxymethyl-1-methylthioferrocene have been obtained with high optical purity by lipase-catalysed resolution of the racemate.

Several mono- and polyacetates of (+)-catechin [(2R,3S)-2-(3,4-di-hydroxyphenyl)-3,4-dihydro-2H-1-benzopyran-3,5,7-triol] have been synthesized by biocatalyzed reactions starting from (+)-catechin or (+)-catechin pentaacetate. In particular, 5-O-acetylcatechin and 7-O-acetylcatechin have been obtained by reaction of catechin with vinyl acetate in the presence of supported Pseudomonas cepacia lipase, while alcoholysis of catechin pentaacetate with 1-butanol catalyzed by the same enzyme yielded 3,3',4',5-O-tetraacetylcatechin and 3,3',4'-O-triacetylcatechin and, under different experimental conditions, 3-O-acetylcatechin.

Acetylation of meso,dl-1,1'-bis(alpha-hydroxyethyl)ferrocene in dry acetone using vinyl acetate as acetyl donor and Pseudomonas cepacia lipase as catalyst allowed the diacetate of the (R,R)-enantiomer and the free (S,S)-diol to be obtained. A concurrent desymmetrization of the meso-diol was also obtained.

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