核磁共振测定手性化合物绝对构型的综述
The Assignment of Absolute Configuration by NMR†
Jose′ Manuel Seco, Emilio Quin˜oa′, and Ricardo Riguera*
Departamento de Quı′mica Orga′nica and Unidad de RMN de Biomole′culas Asociada al CSIC, Universidad de Santiago de Compostela,
E-15782, Santiago de Compostela, Spain
Contents
1. Introduction and Scope 17
2. Methods Based on Chiral Derivatizing Reagents
(CDAs): General Characteristics
19
2.1. Description of the Method 19
2.2. Characteristics of the Auxiliary Reagents 20
2.3. The NMR Spectra of the Derivatives 20
2.4. Importance of the Conformational Equilibrium 21
2.5. Substrates and Derivatives 22
3. Methods Based on Double Derivatization 22
3.1. Application to R-Chiral Secondary Alcohols 22
3.1.1. Methoxytrifluoromethylphenylacetic Acid
(MTPA): Mosher’s Reagent
22
3.1.2. Methoxyphenylacetic Acid (MPA) 33
3.1.3. 9-Anthrylmethoxyacetic Acid (9-AMA) and
Related AMAAs
40
3.1.4. Other Reagents 45
3.2. Application to a-Chiral Primary Alcohols 57
3.2.1. MTPA 58
3.2.2. 9-AMA 61
3.3. Application to R-Chiral Tertiary Alcohols 63
3.3.1. MTPA 63
3.3.2. Methoxy-(2-naphthyl)acetic Acid (2-NMA) 63
3.3.3. The Fucofuranoside Method 64
3.4. Application to R-Chiral Primary Amines 65
3.4.1. MTPA 65
3.4.2. MPA 68
3.4.3. AMAAs 70
3.4.4. Boc-phenylglycine (BPG) 70
3.4.5. Other Reagents 74
3.5. Application to Secondary Amines: MTPA 77
3.6. Application to R-Chiral Carboxylic Acids 79
3.6.1. Ethyl 2-(9-anthryl)-2-hydroxyacetate
(9-AHA) and Related Aryl Alcohols
80
3.6.2. Arylcyclohexanols 82
3.6.3. (S)-Methyl Mandelate. 84
3.6.4. Phenylglycine Dimethyl Amide (PGDA)
and Phenylglycine Methyl Ester (PGME)
85
3.6.5. 1,1￠-Binaphthalene-8,8￠-diol (BNDO) 88
3.7. Application to a-Chiral Carboxylic Acids 89
3.7.1. Arylethylamines 89
3.7.2. PGME 90
3.8. Application to Chiral Sulfoxides: MPA 92
3.9. Application to Chiral Polyhydroxylated
Compounds
92
3.9.1. MPA and 9-AMA 94
3.9.2. MTPA 96
4. Methods Based on a Single Derivatization 99
4.1. Application to R-Chiral Secondary Alcohols 101
4.1.1. 9-AMA Esters: Esterification Shifts 101
4.1.2. Glycosidation Shifts 103
4.1.3. Low-Temperature NMR of MPA Esters 105
4.1.4. Complexation of MPA Esters with
Barium(II)
107
4.2. Application to R-Chiral Primary Amines:
Complexation of MPA Amides with Barium(II)
108
5. New Trends 109
5.1. Hyphenated High-Pressure Liquid
Chromatography (HPLC) NMR-MS
Techniques for Automatization and
Microscale Analysis
109
5.2. Resin-Bound Auxiliaries: The “Mix and
Shake” Method
111
6. Concluding Remarks: A Critical Assessment 113
7. Acknowledgment 114
8. References 114
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