Daria Giacomini

Stereocontrolled total synthesis of the chiral building block (3S,4R)-3- [(R)-1-hydroxyethyl]-4-acetyloxy-azetidin-2-one: a useful synthon for the synthesis of (+)-thienamycin, carbapenems and penems.

Abstract A total stereocontrolled synthesis of ( 1 ), an intermediate in the synthesis of (+)-thienamycin, carbapenems and penems, based on a strategy that uses the S(-)hydroxy ethylbutyrate as chiral building block, is reported.

β-lactams from esters and silylimines: A revaluation. Synthesis of N-unsubstituted 4-alkyl-β-lactams

Abstract The first preparation of enolizable silylimines is reported. The “in situ” trapping of these species with lithium enolates of esters gives rise in fairly good yields to N-unsubstituted 4-alkyl-β-lactams.

Studies on N-metallo imines: synthesis of N-unsubstituted aziridines from N-trimethylsilyl imine and lithium enolates of α-halo esters.

Abstract Addition of lithium enolates of 2-halo carboxylic esters to N-trimethylsilyl imines results in the formation of 1 H -aziridine derivatives, in the Darzens fashion, with high cis -selectivity.

Metallo-imines: useful reagents in organic synthesis

Ihe preparation of aluminum, silicon and tin imines from nitriles, aldehydes and ketones, enolizable as well as nonenolizable ones, is reported. The reactivity of these relatively new organometallic compounds has also been explored.

N-metallo imines: A new approach to α-amino alcohols from aldehydes.

Abstract The addition of lithium alkyls or Grignard reagents to the in situ generated O-protected α-hydroxy-N- trimethylsilylimines proceeds in good yields and highly stereocontrolled manner to produce 1,2 -aminols.

A synthetic approach to azetidinones from nitriles and lithiumtriethoxyaluminium hydride.

Abstract A convenient one-pot process for direct conversion of nitriles to 3,4-disubstituted azetidinones has been developed.

Solvation of the Carbonyl Compound as a Predominant Factor in the Diastereofacial Selectivity of Nucleophilic Addition.

Temperature-dependent selectivity in nucleophilic additions is affected by the solvent. The inversion temperature (marked with arrows in the graph) that appears in the nonlinear Eyring plots of ln (anti/syn) versus temperature for the addition of butyllithium to an O-protected alpha-hydroxy aldehyde 1 does not depend on nucleophiles (nBuLi (black triangle), tBuLi (*)), but on the solvent. Its value can be obtained from a plot of the (13)C NMR chemical shift of C=O versus temperature. TBDMS=tBuMe(2)Si.

A practical synthesis of a key intermediate for the production of β-lactam antibiotics

Abstract N-(p-methoxyphenyl)-hexahydro-1,3,5-triazine in presence of a Lewis acid and (R)-3-(t-butyldimethylsilyloxy)butyric acid chloride with Et3N directly furnish (3S,1′R)-N-p-methoxyphenyl-3-(1-t-butyldimethylsilyloxy)ethylazetidin-2-one with good diastereo-selectivity. This product is transformed into the 4-acetoxy-azetidinone 1, a key intermediate in the synthesis of β-lactam antibiotics.

ACYCLIC STEREOCONTROL IN THE ADDITION OF TRIMETHYLSILYL CYANIDE TO N-SUBSTITUTED IMINES OF (2S)-LACTIC ALDEHYDE

Abstract The cyanosilylation of a series of N -substituted lactaldehyde imines is reported. The trimethylsilylcyanide addition affords optically active α-amino nitriles. All the imines show a syn diastereofacial selectivity that is maintained irrespective to the nature of the Lewis acid employed and even remains in the noncatalyzed reaction.

Preparation of 1,2 aminols from cyanohydrins viaN-diisobutylaluminium imines.

Abstract The N-Aluminium imines derived from cyanohydrins have been used in the synthesis of α-amino alcohols with high diastereoselectivity.