ChemInform Abstract: Amino Acid Homologation by the Blaise Reaction: A New Entry into Nitrogen Heterocycles.

Abstract

Imidazole derivatives R 0190Amino Acid Homologation by the Blaise Reaction: A New Entry into Nitrogen Heterocycles. -Treatment of Cbz-protected amino nitriles of type (IV) derived from α-amino acids with bromoacetate and subsequent base-mediated cyclization provides a new approach to imidazolidinones like (VI). These compounds smoothly undergo stereoselective reduction to give cis-and/or trans-substituted imidazolidinones. Hydrolysis of the latter does not yield the expected β,γ-diamino acids but cyclization products like (IX) and (X). Blaise reaction of the functionalized amino nitrile (XIII) provides the lactam (XIV) instead of the corresponding imidazolidinone. (XIV) undergoes stereoselective reduction giving the trans-substituted lactam (XV). -(HOANG, C. T.; BOUILLERE, F.; JOHANNESEN, S.; ZULAUF, A.; PANEL, C.; POUILHES, A.; GORI, D.; ALEZRA*, V.; KOUKLOVSKY, C.; J.

Constrained Cyclic β,γ‐Diamino Acids from Glutamic Acid: Synthesis of Both Diastereomers and Unexpected Kinetic Resolution

“…For example, the natural α-amino acid L-proline is known to form polyproline helices, [1] or to generate turns when associated with glycine. [20][21][22][23][24][25] This pattern is present in some biologically active compounds such as pseudotheonamide A 1 , [26] aminocarnitine, [27] and deoxyaminostatine, [28] but the main interest in this motif lies in its use as either a -amino acid or a γ-amino acid building block for foldamers. [2][3][4][5][6][7][8][9] A large variety of helices, [10][11][12][13][14] turns, [15] sheets, [16] and ribbons [17,18] have been observed in this way, even in the less explored area of γ-peptides.…”

Frozen Chirality of Tertiary Aromatic Amides: Access to Enantioenriched Tertiary α‐Amino Acid or Amino Alcohol without Chiral Reagent

“…Our research group has, over a few years, developed several asymmetric syntheses of nonproteinogenic amino acids starting from natural α‐amino acids, by using the initial chirality of the reacting α‐amino acid as the unique source of chirality. We have thus synthesized enantiopure β,γ‐diamino acids through a classical diastereoselective synthesis and quaternary α‐amino acids relying on the Memory of Chirality (MOC) principle . The next step was an extension of this latter methodology to the great challenge of absolute asymmetric synthesis of tertiary α‐amino acids; that is, to get rid of the initial chirality and to start from the simplest achiral α‐amino acid, glycine.…”