NK++ClCH2CO2C2H5→一 N-CH, CO,C,H Ethyl chloroacetate (氯代醋酸乙酯) Potassium phthalimide (苯邻二甲酰亚胺钾) HCO COOH (1)KOH/H,O (2)HCI CHoH COOH Glycine Phthalic acid (氨基乙酸)(邻苯二甲酸) 243C THE STRECKER SYNTHESIS Treating an aldehyde with ammonia and hydrogen cyanide produces an a-amino nitrile. Hydrolysis of the nitrile group of the a-amino nitrile converts the latter to an a-amino acid
N - K + O O + ClCH2CO2C2H5 N O O CH2CO2C2H5 (1) KOH / H2O (2) HCl COOH COOH + C2H5OH CH2CO2 - NH3 + + Potassium phthalimide (苯邻二甲酰亚胺钾） Ethyl chloroacetate (氯代醋酸乙酯） Glycine (氨基乙酸) Phthalic acid (邻苯二甲酸) 24.3C THE STRECKER SYNTHESIS Treating an aldehyde with ammonia and hydrogen cyanide produces an α-amino nitrile. Hydrolysis of the nitrile group of the α-amino nitrile converts the latter to an α-amino acid
RCHO+NH3+HCN→ RCHCN H3O, heat, RCHCO2 NH NH a-Amino nitrile a -Amino acid Mechanism of the first step OH H2O RCH + NH3 RCHNH3= rchnh CN CN RCH=NH- RCHNH- RCHNH 24.3D RESOLUTION OF DL-AMINO ACIDS
RCHO + NH3 + HCN RCHCN NH2 H3O + , heat NH3 + RCHCO2 - α-Amino nitrile α-Amino acid Mechanism of the first step: RCH + NH3 RCHNH3 + RCHNH2 O O - OH -H2 O RCH=NH RCHNH - CN H + RCHNH2 CN 24.3D RESOLUTION OF DL-AMINO ACIDS
One interesting method for resolving amino acids is based on the use of enzymes called deacylase DL-RCHCO,(CH3 CO)O, DL-RCHCO,H deacylase CH3COOH NH NHCOCH CO2 CO2 thrN -H HrCOChN R R L-Amino acid D-N-Acylamino acid (L-氨基酸) (D-N-酰氨基酸) Easily separated 243E STEREOSELECTIVE SYNTHESIS OF AMINO ACIDS
One interesting method for resolving amino acids is based on the use of enzymes called deacylases. RCHCO2 D - L NH3 + (CH3CO) 2O DL RCHCO2 H NHCOCH3 deacylase +H3 N H CO2 - R H3 COCHN H CO2 - R + Easily separated L-Amino acid (L-氨基酸） D-N-Acylamino acid (D-N-酰氨基酸） CH3 COOH 24.3E STEREOSELECTIVE SYNTHESIS OF AMINO ACIDS
Producing only the naturally occurring L-amino acid has been realized through the use of chiral hydrogenation catalysts from transition metals. One of which is called"(R)-prophos H3C H (C6H5hP P(C6Hsh (R)-Prophe [Rh(NBD)2]CIO4 +()-prophos- [Rh(R)-prophos)(NBD)]CIO4+ NBD Chiral rhodium complex (手性铑配合物) Hydrolysis of N-acetyl group under this chiral rhodium complex yields L-alanine. Because the hydrogenation catalyst is chiral, it transfers its hydrogen atoms in a stereoselective way. This type of reaction is called asymmetric synthesis
Producing only the naturally occurring L-amino acid has been realized through the use of chiral hydrogenation catalysts from transition metals. One of which is called “(R)-prophos”. CH2 (C6 H5 ) 2 P H H3 C P(C6 H5 ) 2 (R)-Prophos [Rh(NBD) 2 ]ClO4 + (R)-prophos [Rh((R)-prophos)(NBD)]ClO4 Chiral rhodium complex (手性铑配合物） + NBD Hydrolysis of N-acetyl group under this chiral rhodium complex yields L-alanine. Because the hydrogenation catalyst is chiral, it transfers its hydrogen atoms in a stereoselective way. This type of reaction is called asymmetric synthesis
CH2=C-CO2H [Rh(R)-prophos)(H2)solvent)2]+ HcI COOH NHCOCH H3COCHN 2-Acetylaminopropenoic acid N-Acetyl-L-alanine (2-乙酰胺基丙烯酸) (N-乙酰基-L-丙胺酸) (I)OH, H2O, heat, (2)H3O HcI +H3N L-alanine (L-丙胺酸) 24.4 ANALYSIS OF AMINO ACID MIXTURES Enzymes can cause a-amino acids to polymerize through the elimination of water
CH2 =C _ CO2H NHCOCH3 [Rh((R)-prophos)(H2 )(solvent) 2 ] + H2 COOH H3 COCHN H3 C H N-Acetyl-L-alanine (N-乙酰基-L-丙胺酸) (1) OH - , H2O, heat, (2) H3 O+ CO2 - +H3N H3C H L-alanine (L-丙胺酸) 2-Acetylaminopropenoic acid (2-乙酰胺 基 丙 烯 酸 ） 24.4 ANALYSIS OF AMINO ACID MIXTURES Enzymes can cause α-amino acids to polymerize through the elimination of water: