Ada Manzocchi

Polyetylene Glycols as host solvents: applications to organic synthesis☆

Abstract Polyethylene glycols (PEG) are fair solvents for inorganic salts and organic substrates; their use in some organic reactions is described.

Enantioselective transesterification of 2-methyl-1,3-propanediol derivatives catalyzed by Pseudomonas fluorescens lipase in an organic solvent

Abstract The irreversible transesterification of racemic 2-methyl-1,3-propanediol derivatives, the monoethers, 3a , 3b , 5a , and the monobenzoate 5b , with vinyl acetate catalyzed by Pseudomonas fluorescens lipase in chloroform affords enantiomerically pure chiral synthons.

Oxidative decarboxylation of arylacetic acids by means of tetrabutylammonium periodate

Abstract Tetrabutylammonium periodate (TBAPI) in refluxing dioxane is able to convert arylacetic acids into the corresponding nor-aldehydes in good yields.

Regio- and enantioselectivity of Pseudomonas cepacia lipase in the transesterification of 2-substituted-1,4-butanediols

Abstract The transesterification of 2-substituted-1,4-butanediols 1a , 2a and 3a with vinyl acetate catalyzed by the Pseudomonas cepacia lipase in organic solvents affords preferentially the 1-acetate, the highest regioselectivity having been found for the epoxydiol 3a , which is enantioselectively resolved [86% ee for the unreacted (S)-(−)- 3a ].

Baker's yeast-mediated reduction of α-hydroxy ketones and derivatives: The steric course of the biotransformation

Abstract The results from the bakers yeast-mediated reduction of the acetates 3a-d and the methyl ethers 5a-d were compared with the same biotransformation which converts the α-hydroxy ketones 1a-d into the (R)-diols 2a-d (90–98%ee); the acetates 3a-d afford the (S)-monoacetates 4a-d (72–94% ee) and the methyl ethers 5a-d are reduced to the (R)-monoethers 6a-d (64–76% ce).

Formation of a cysteine-acrylamide adduct in isoelectric focusing gels

Abstract Radical polymerization of acrylamide gels, even under carefully controlled conditions, rarely exceeds 90% conversion of the monomers into the polymer matrix. Thus, a 5%T gel will contain 30–60 mM unreacted free acrylamide. During isoelectric focusing (IEF), at pH > 8, free SH groups in proteins can rapidly react with the double bond of the free monomers in the gel. When Cys is incubated at room temperature with 30 mM acrylamide at pH 9.0, addition to the double bond is complete in 90 min. The existence of the Cys-acrylamide adduct has been ascertained by NMR, mass spectra and elemental analysis of the purified compound. It is suggested that acrylamide gels for IEF be treated with the same protocol adopted since 1980 for immobilized pH gradient gels: an “empty” matrix should be prepared, washed free of contaminants (unreacted monomers and catalysts,e.g., 3 × 1 h in excess distilled water) and stored dry for subsequent use.

Studies on the regio- and enantioselectivity of the lipase-catalyzed transesterification of 1′- and 2′-naphthyl alcohols in organic solvent

The Pseudomonas cepacia lipase preferentially acylates the 2′-regioisomers of a few 1′- and 2′-naphthyl alcohols; in the case of compounds 3a, 3c, 4a, 4c the (R)-alcohols (65→98% ee) and the (S)-acetates (62–98% ee) are formed.

1H, 13C and 15N NMR assignments for N6-isopentenyladenosine/inosine analogues

The complete 1H, 13C and 15N NMR signals assignments of some new isopentenyladenosine analogues were achieved using one‐ and two‐dimensional experiments (gs‐NOESY, gs‐HMQC and gs‐HMBC). Copyright

Structure-stability relationship of Immobiline chemicals for isoelectric focusing as monitored by capillary zone electrophoresis

Abstract An acrylamido buffer for isoelectric focusing in immobilized pH gradients, 1-acryloyl-4-methylpiperazine (p K = 6.85 at 25°C), was synthesized. As it is a disubstituted amide, it was thought that it would be much more resistant to alkaline hydrolysis. In reality, it degraded rapidly in 0.1 M sodium hydroxide solution at 70°C (86% in 6 h). Therefore, the stability of Immobiline buffers of p K 9.3, 8.5, 7.0 and 6.2 was investigated. Under the same hydrolysis condition, the degradation was 11%, 22%, 26% and 34%, in order of decreasing p K values. The kinetics of degradation were monitored by capillary zone electrophoresis in 0.1 M borate buffer (pH 9). The decrease of the main Immobiline peak and the appearance of its hydrolytic products, acrylic acid and a diamine, could be easily measured. The following general rules were derived: when the nitrogen engaged in the amido bond is inserted into a cyclic structure ( e.g. , 1-acryloyl-4-methylpiperazine) there is very little protection against hydrolysis, and conversely, when this nitrogen carries flexible, fairly long substituents (4–5 atoms long) much stronger shielding and protection of the amido bond can be obtained. These findings helped in designing new acrylamido derivatives strongly resistant to chemical degradation.

Lipolytic activity of porcine pancreas lipase on fatty acid esters of dialkylglycerols: a structural basis for the design of new substrates for the assay of pancreatic lipases activity

For the design of new synthetic substrates for the assay of pancreatic lipases activity, acyl dialkylglycerols of variable chain length were prepared. Titrimetric assay of these substrates showed the highest lipolytic activity of porcine pancreas lipase (pPL) with butanoyl dibutylglycerol. The activity is lower but comparable to that shown by pPL towards the classical substrate tributyrin. The 4-nitrophenylcarbonate of 1,2-di-O-butylglycerol, has been prepared and proposed as synthetic substrate for a new spectrophotometric assay of pancreatic lipases.