Maurizio Taddei

Mild Reduction of Carboxylic Acids to Alcohols Using Cyanuric Chloride and Sodium Borohydride

Several carboxylic acids, including N-Boo, N-Cbz and N-Fmoe amino acids were reduced to the corresponding alcohols by activation of the carboxy function with cyanuric chloride and N-methylmorpholine followed by reduction with aqueous sodium borohydride.

Synthesis of N-Fmoc-α-amino acids carrying the four DNA nucleobases in the side chain.

Four new N-Fmoc α-amino acids carrying a nucleobase in the side chain were prepared starting from l-glutamic acid. N-Boc-glutamic acid α benzyl ester underwent a radical decarboxylation in the presence of CBrCl3 to give the corresponding 2-amino-4-bromobutanoic acid derivative. The four nucleobases (adenine, cytosine, thymine and guanine) were introduced “via” nucleophilic substitution of the bromide using a different synthetic protocol for each base. The Boc protection was changed to Fmoc and the benzyl ester deprotected to give the four amino acids in good yields and in a suitable form for solid phase peptide synthesis. The preparation of the insecticidal dipeptide NK 374200 is also described.

Ring opening of phenylaziridines with allylsilanes

Abstract N-tosyl phenylaziridines are opened regioselectively with allylsilanes in presence of BF 3 .Et 2 O to form γ-amino olefins. During the reaction a formal [3+2] cycloaddition produced the corresponding pyrrolidines, amenable to the open chain compounds with TBAF.

STEREOCONVERGENT SYNTHESIS OF (2S,3S,8S,9S,4E,6E)-N-BOC-ADDA STARTING FROM(S)-SERINE AND (S)-PHENYLLACTIC ACID

Abstract The important naturally occurring β-amino acid N-Boc-ADDA is prepared following a disconnection of the CC bond between the two E,E double bonds. The stereochemistry of the two synthons was controlled using the alkylation of chiral bromoallenes derived from naturally occurring (S)-serine and (S)-phenyllactic acid. The cupration of bromoallenes derived from (S)-serine also provides a general method for the synthesis of chiral β-alkylated aspartic acid derivatives.

A simple preparation of N-vinyl derivatives of DNA nucleobases

Abstract 1-Vinylpyrimidines and 9-vinylpurines have been prepared via selective alkylation of the heterocyclic ring with 1,2-dibromoethane (or 1,2-dibromopropanol) followed by dehydrobromination with sodium ethoxide in ethanol/ DMF.

A sensitive visual test for detection of OH groups on resin

Abstract The presence of an OH group on a resin can be visualized with a colourimetric test based on the anchoring of a carboxylic dye on a chlorotriazine covalently linked to the hydroxyl group. 2,4,6-Trichloro-[1,3,5]-triazine (TCT) and Alizarin R (AliR) colour OH containing beads as deep yellow–red globes.

small ring constrained peptidomimetics. synthesis of aziridine parallel β-sheet mimetics.

Abstract The synthesis of a series of novel amino acids and peptides containing an aziridine ring is described. Their preparation is based on the Gabriel-Cromwell reaction of amino acids or peptides with different 2-bromo acrylates and acrylamides. These products are constituted by a turned scaffold (the aziridine) where two parallel peptidic strands can be grown to produce a β-sheet mimetic.

CrCl2 Mediated addition of allylic halides or phosphates to N-protected α-amino aldehydes. Stereocontrolled synthesis of a new core for C2 symmetric HIV-protease inhibitors

The addition of γ-monosubstituted allylchromium(III) reagents to N-protected α-amino aldehydes proceeds in a stereoconvergent manner in contrast with the case of the unsubstituted reagents, where the stereoselectivity depends on the nature of the group bonded to the nitrogen. The chromium(III) reagent derived from 3-chloromethyl-2-trimethylsilyl-1-propene was used to prepare a C2 symmetric HIV-protease inhibitor.

Nucleophilic substitution of protected 2-amino-4-butanoic acid. An easy route to exotic amino acids and conformationally constrained peptides

Abstract The synthesis of a series of novel α-amino acids based on the nucleophilic substitution of protected 2-amino-4-bromobutanoic acid ( 1 ) is described. Basic, acidic or neutral amino acids can be obtained; chimerical amino acids carrying a coenzyme type structure in the side chain, multifunctional amino acids for the synthesis of cross-linked peptides or dendrimers and conformationally constrained peptides can also be obtained.

SYNTHESIS OF AMPHIPHILIC POLYHYDROXYLATED PYRROLIDINES AS POTENTIAL GLYCOSIDASE INHIBITORS

Abstract Several polyhydroxylated pyrrolidines with an aliphatic long chain on the ring nitrogen were prepared starting from d -mannitol. An amphiphilic bis-azasugar scaffold has been also prepared. These products behave as cationic surfactants and show a promising anti HIV-1 activity.