Gianna Reginato

A new stereoselective synthesis of chiral γ-functionalized (E)-allylic amines

Abstract Chiral t -Boc protected propargylic amines have been obtained starting from aminoaldehydes derived from natural aminoacids. Stannylcupration of these substrates affords an easy regio- and stereocontrolled route to the corresponding γ-stannylated ( E )-allylamines which are useful intermediates for the synthesis of the corresponding γ-funtionalized allylic systems.

Synthesis of N-Boc-α-amino acids with nucleobase residues as building blocks for the preparation of chiral PNA (peptidic nucleic acids)

Abstract N-Boc-Glutamic acid α-benzyl ester was transformed into 4-bromo-2-(tert-butoxycarbonylamino)-butyric acid benzyl ester using the Barton-Crich protocol. This bromo derivative undergoes nucleophilic substitution with nucleobases to give optically active N-Boc-4-adeninbutyrine (Boc-Aby), N-Boc-4-thyminbutyrine (Boc-Tby), N-Boc-4-guaninbutyrine (Boc-Gby) or N-Boc-4-cytosinbutyrine (Boc-Cby), useful building blocks for the synthesis of chiral peptidic nucleic acids (PNA).

Practical one-step synthesis of ethynylglycine synthon from Garner's aldehyde

A simple, efficient and practical synthesis of (R)-2,2-dimethyl-3-(tert-butoxycarbonyl)-4-ethynyloxazolidine (ethynylglycine synthon) is described. The method involves in situ formation of dimethyl 1-diazo-2-oxopropyl phosphonate from dimethyl 2-oxopropyl phosphonate and 4-acetamidobenzene sulfonyl azide and one-pot reaction on Garners aldehyde. The reaction has been extended to other aminoaldehydes.

Excited State Geometries and Vertical Emission Energies of Solvated Dyes for DSSC: A PCM/TD-DFT Benchmark Study

The ability of Time-Dependent Density Functional Theory (TD-DFT) to provide excited state geometries and reproduce emission energies of organic D-π-A dyes designed for DSSC applications is evaluated. The performance of six functionals (CAM-B3LYP, MPW1K, ωB97X-D, LC-BLYP, LC-ωPBE, and M06-HF) in combination with three basis sets (cc-pVDZ, 6-31+G(d,p), and 6-311+G(2d,p)) has been analyzed. Solvent effects have been taken into account by means of a Polarizable Continuum Model in both LR and SS formalisms. Our LR-PCM/TD-DFT results show that accurate emission energies are obtained only when solvent effects are included in the computation of excited state geometries and when a range separated hybrid functional is used. Vertical emission energies are reproduced with a mean absolute error of at most 0.2 eV. The accuracy is further improved using the SS-PCM formalism.

Solid phase synthesis of a self complementary (antiparallel) chiral peptidic nucleic acid strand

Abstract The solid phase synthesis (Boc protocol) of a new chiral peptidic nucleic acid formed exclusively by α-amino acids is described. The product showed a defined T m suggesting the possibility of a DNA-like self-aggregation in solution

Bis(trimethylsilyl)sulfide based thionation of carbonyl compounds : synthesis of thioketones

Abstract A wide range of thioketones may be conveniently obtained by silyl triflate promoted bis(trimethylsilyl)sulfide thionation of ketones.

Base-promoted elaboration of aziridines

The base-promoted isomerization of aziridines to allyl amines is still an almost unknown reaction. However, the use of superbasic reagents has shown to be able to promote a regio- and stereoselective conversion of monocyclic and bicyclic sulfonyl aziridines. Moreover, the use of alkoxy substituted aziridines opens new routes to non-natural α- and β-amino acids.

Terminal 1-halo- 1 and 1-pseudohalo-1-alkynes via bis(trimethylsilyl)peroxide (BTMSPO) promoted Umpolung transfer of Halides and pseudohalides.

Abstract Reaction of terminal acetylenes with readily available and inexpensive copper and zinc halides and pseudo-halides and BTMSPO has been found to be an effective and general route for obtaining, in the absence of bases and under mild conditions, 1-halo- and 1-pseudohalo-1-alkynes in generally good yields.

Useful base promoted elaborations of oxiranyl ethers

Abstract Functionalized oxiranyl ethers can be regio- and stereoselectively converted into hydroxy oxetanes or cis -diols by treatment with organometallic bases. These two rearrangements can be conveniently carried out either using different reaction conditions starting from the oxirane or in two consecutive steps from the oxirane via the oxetane.

Stannylcupration of γ-heterosubstituted acetylenic esters: A new route to 4-stannylated five membered N- and O- heterocycles

Abstract 4-Tributylstannyl,2-(5H)-furanone and pyrrolone have been prepared in good yields by addition of mixed stannylcuprate reagent on γ-amino and γ-hydroxy acetylenic esters. The use of these compounds as useful intermediates for the selective functionalization of these heterocyclic rings is discussed.