A Novel Highly Selective Chiral Auxiliary for the Asymmetric Synthesis ofl- andd-α-Amino Acid Derivatives via a Multicomponent Ugi Reaction

Abstract

This paper describes the synthesis of a bicyclic beta-amino acid scaffold in both pure enantiomeric forms and its application as chiral auxiliary in an intramolecular version of the Ugi multicomponent reaction (U-5C-4CR) to prepare alpha-amino acid derivatives of both D- and L-series in a straightforward and very stereoselective manner. The mild conditions required for the Ugi condensation and for the removal of the chiral auxiliary make this method very attractive to prepare a wide range of differently structured N-alkylated and unalkylated amino acid derivatives.

A Marriage of Convenience: Combining the Power of Isocyanide‐Based Multicomponent Reactions with the Versatility of (Hetero)norbornene Chemistry

“…The oxanorbornene derivative 26 (Scheme 9) also behaved in the same manner. Although its synthesis was more complex, [32] the additional value of the double bond will become evident below.…”

“…In analogy with the approach illustrated in Section 3, we first investigated the use of the bicycles 26 as chiral auxiliaries and found that the optically pure α-aminoamides 47 (Scheme 17) could be conveniently obtained by a simple two-step procedure involving retro-Diels-Alder reactions of Ugi adducts 29 with loss of furan and acid-mediated cleavage of the resulting enamines 46. [32] Scheme 17. Ugi-mediated synthesis of enantiomerically pure α-amino acid derivatives through employment of an oxanorbornenyl chiral auxiliary.…”

Synthesis of chiral 2-furyl and 3-nitro-7-oxabicyclo[2.2.1]heptane derivatives from sugars

“…Leaving aside previous work from our group, 3,4 to the best of our knowledge there are no references on the preparation of chiral 7-oxanitronorbornenes. 5 Moreover, they could not be synthesized from chiral nitroacrylates as dienophiles, 6 and only a few amines resulting from the reduction of racemic 7-oxanitronorbornenes have been resolved. 5 On the other hand, sugar derivatives with a furan ring in their structures have received attention as precursors in the preparation of biologically important compounds, such as tunicamines (main component of numerous antibiotics), 7 C-nucleosides, 8 peptidomimetics, 9 and spiro carbon linked disaccharides.…”

“…5 Moreover, they could not be synthesized from chiral nitroacrylates as dienophiles, 6 and only a few amines resulting from the reduction of racemic 7-oxanitronorbornenes have been resolved. 5 On the other hand, sugar derivatives with a furan ring in their structures have received attention as precursors in the preparation of biologically important compounds, such as tunicamines (main component of numerous antibiotics), 7 C-nucleosides, 8 peptidomimetics, 9 and spiro carbon linked disaccharides. 10 In most cases, furyl sugars can be prepared by either treatment of activated furans with the appropriate acceptors, 7,8a,10,11 or building the furan moiety from non-furylic precursors.…”

One-pot preparation of β–amido ketones and esters in four-component condensation reaction using ferric hydrogensulfate as effective and reusable catalyst

“…[1][2][3][4][5][6][7][8] Amido-or amino ketone derivatives are important for their biological, pharmaceutical properties, 9,10 and in the preparation of antibiotic drugs such as nikomycine or neopolyoxines. 11,12 The common procedure for the synthesis of these class compounds is the Dakin-West reaction [13][14][15] which involves the condensation of α-amino acids with acetic anhydride in the presence of suitable base, [3][4][5][6][7][8][9][10][11][12][13][14][15][16] these reaction produce α-acetamido ketones ZnO, 29 Amberlyst-15, 30 iodine 31 and FeCl 3 .6H 2 O. 32 Ferric salts have applied for the formation of carbon-nitrogen and carbon-oxygen bonds in organic synthesis.…”