Product Class 13: 1,2,3-Triazoles

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Scheme 52 Selective Synthesis of Isomeric 1H-1,2,3-Triazoles from Propargyl Azides [148] MeO 134 N 3 NH3 62% NH3, NaOH 75% The intramolecular 1,3-dipolar cycloaddition of an azide group with a C”C bond has been used extensively for the synthesis of nonclassical polycyclic â-lactams. [149–154] 13.13.1.1.3.1.1.3.6 Variation 6: Addition of Azides to Alkoxyalkynes Nitrophenyl azides 138 undergo cycloaddition reactions with 1-methoxyalk-1-ynes 137 at room temperature to give 1H-1,2,3-triazoles 139 in low yields (R 1 = Et; X = H, 22%) or the corresponding ring-opened isomeric Æ-diazocarboximidates 140 (R 1 = Me, 52%; R 1 = Et, 75%) (Scheme 53). [155] The reaction of ethoxyacetylene with 4-methxoyphenyl azide and 4-nitrophenyl azide also gives the corresponding 1-aryl-5-ethoxy-1H-1,2,3-triazoles. [103] MeO H 2N H 2N MeO 135 136 Scheme 53 Addition of Aryl Azides to 1-Methoxyalk-1-ynes [155] R 1 137 OMe R 1 = Me, Et; X = H, NO 2 + FOR PERSONAL USE ONLY 452 Science of Synthesis 13.13 1,2,3-Triazoles O2N N 3 138 NO 2 X CHCl3, rt 3−10 d N H N H N N N N MeO R 1 N 139 N N O 2N X X = NO 2 NO 2 R 1 N 2 MeO N O2N X Similarly, 5-ethoxy-1H-1,2,3-triazoles 143 are obtained from the reaction of ethoxyacetylene (141) with phenyl azide, substituted phenyl azides [156] and hetaryl azides [114] 142 (Scheme 54). The best yield is obtained with phenyl azide (87%). With 2-nitrophenyl azide, and 4-nitrophenyl azide the yields are very low (6–12%). A. C. TomØ, Section 13.13, Science of Synthesis, 2004 Georg Thieme Verlag KG 140 NO2
Scheme 54 Addition of Azides to Ethoxyacetylene [114,156] H OEt + R1N3 141 R 1 = aryl, O O 142 6−87% 5-Ethoxy-1-(6-methyl-2-oxo-2H-pyran-4-yl)-1H-1,2,3-triazole (143,R 1 = 6-methyl-2-oxo-2Hpyran-4-yl); Typical Procedure: [114] A mixture of 4-azido-6-methyl-2H-pyran-2-one (0.77 g, 5.09 mmol), ethoxyacetylene (7.13 mmol, from a 50% soln in hexanes) and anhyd THF (18 mL) was left in a closed reactor for 7 d. The resulting precipitate of the product was collected by filtration and the filtrate was left 7 d more at 308C to give a second crop. The combined precipitates were washed with hexane to afford the pure product; yield: 24% (57% with respect to consumed azide 142); mp 159–1618C. EtO 143 N N N R1 13.13.1.1.3.1.1.4 Method 4: Addition of Ethyl Azidoformate and Cyanogen Azide to Alkynes Ethyl azidoformate (144) undergoes addition to phenylacetylene to give 1,2,3-triazoles. If the reaction is carried out at 508C (3 weeks) a mixture of the 1,4- and 1,5-disubstituted triazoles is obtained in a ratio of about 53:47 and an overall yield of 36% (Scheme 55). [157] If the reaction is performed at 1308C the two initially formed triazoles 145/146 isomerize to ethyl 4-phenyl-2H-1,2,3-triazole-2-carboxylate (147) and this is the isolated triazole product (16%). Under these reaction conditions, 2-ethoxy-4(or 5)-phenyloxazole 148 (16%) is also obtained. [157,158] The formation of this compound is due to the addition of (ethoxycarbonyl)nitrene (generated by thermal decomposition of the azide) to phenylacetylene. The reaction of ethyl azidoformate with dimethyl acetylenedicarboxylate and methyl propynoate also gives the corresponding triazoles (23 and 50% yield, respectively) and 2-ethoxyoxazoles (3%). [158] Scheme 55 Addition of Ethyl Azidoformate to Phenylacetylene [157,158] Ph H + N3CO2Et 144 FOR PERSONAL USE ONLY 13.13.1 Monocyclic N-Unsubstituted and 1-Substituted 1,2,3-Triazoles 453 50 o C 36% 130 o C Ph N 145 N N CO 2Et + 53:47 Ph N 146 N N CO 2Et Ph Ph N N N N CO2Et + O OEt 147 16% 148 or isomer 16% for references see p 587 A. C. TomØ, Section 13.13, Science of Synthesis, 2004 Georg Thieme Verlag KG
Page 1 and 2: 13.13 Product Class 13: 1,2,3-Triaz
Page 3 and 4: Scheme 3 Ring-Chain Tautomerism in
Page 5 and 6: Scheme 6 Reaction of Ethyl 2-Diazo-
Page 7 and 8: Condensation of 2-Diazo-3-oxoaldehy
Page 9 and 10: Scheme 12 Reaction of 2-(Benzoyloxy
Page 11 and 12: 83%). [42] The 3-diazobenzo[b]thiop
Page 13 and 14: Scheme 17 Reaction of Activated Nit
Page 15 and 16: Scheme 20 Synthesis of 4,5-Diaryl-1
Page 17 and 18: Scheme 24 Addition of Diazomethane
Page 19 and 20: 13.13.1.1.2.1.3.1 Variation 1: From
Page 21 and 22: Scheme 31 Reaction of Organometalli
Page 23 and 24: FOR PERSONAL USE ONLY 13.13.1 Monoc
Page 25 and 26: 13.13.1.1.3.1.1.1 Method 1: Additio
Page 27 and 28: Scheme 38 Addition of Aluminum Azid
Page 29 and 30: R 1 R 2 Conditions Yield (%) Ref (E
Page 31 and 32: R 1 R2 Conditions Yield (%) Ref 93
Page 33 and 34: Scheme 45 Recognition-Mediated Reac
Page 35 and 36: The complementary method, i.e. reac
Page 37: Scheme 51 Synthesis of 1H-1,2,3-Tri
Page 41 and 42: Scheme 57 Addition of Sulfonyl Azid
Page 43 and 44: 13.13.1.1.3.1.1.7 Method 7: Additio
Page 45 and 46: azide. [187] Ethyl 3-(4-nitrophenyl
Page 47 and 48: with Et 2O (two minor dihydrotriazo
Page 49 and 50: The reaction of azides with norborn
Page 51 and 52: Scheme 73 Addition of Phenyl Azide
Page 53 and 54: Scheme 76 Addition of Azides to Æ-
Page 55 and 56: Scheme 78 Addition of Azides to Ena
Page 57 and 58: Scheme 82 Synthesis of 4-(Aminometh
Page 59 and 60: 13.13.1.1.3.1.2.6.2 Variation 2: Ad
Page 61 and 62: Scheme 88 Reaction of Azides with V
Page 63 and 64: Aroylketene dithioacetals 282 react
Page 65 and 66: Scheme 95 Reaction of Azides with 1
Page 67 and 68: Scheme 98 Reaction of Dimethyl 3-Ox
Page 69 and 70: Scheme 102 Reaction of Tosyl Azide
Page 71 and 72: R 1 R 2 Conditions Yield (%) Ref N
Page 73 and 74: 13.13.1.1.4 By Formation of One N-N
Page 75 and 76: Scheme 112 Cyclization of Æ-Hydrox
Page 77 and 78: Scheme 115 Cyclization of 1,2-Diket
Page 79 and 80: Scheme 118 Cyclization of 1,2-Diket
Page 81 and 82: Scheme 121 Isomerization of 1-(Aryl
Page 83 and 84: 13.13.1.2 Synthesis by Ring Transfo
Page 85 and 86: Scheme 127 Reaction of Diazoalkanes
Page 87 and 88: Scheme 129 Oxidative Dehydrogenatio
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13.13.1.4 Synthesis by Substituent
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13.13.1.4.1.1.2 Method 2: N-Trimeth
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08C). [434] Reaction of 1,2,3-triaz
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Scheme 141 Arylation of 1-Benzyloxy
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Scheme 144 Reaction of Triazoles wi
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Scheme 148 Halogenation of 1,2,3-Tr
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Scheme 153 N-Hydroxylation of 1H-1,
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13.13.1.4.1.3 Of Carbon Functionali
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Scheme 161 Hydrolysis of O-Aryl-1H-
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Scheme 166 Catalytic Hydrogenation
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Scheme 170 Substitution of Diazoniu
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Scheme 174 Preparation of 1-Substit
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Scheme 178 Isomerization of 1-Alkyl
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Scheme 181 2-Allyl-2H-1,2,3-triazol
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Scheme 186 Cyclization of N-Unsubst
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with nitrous acid gives the corresp
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13.13.2.1.3.1.4 Method 4: Cyclizati
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Scheme 201 Synthesis of 2-Alkyl-5-n
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Scheme 207 Synthesis of 2H-1,2,3-Tr
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Scheme 209 Proposed Structures for
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5,6-Dinitro-1H-benzotriazole [601,R
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Scheme 215 Synthesis of Benzotriazo
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(15 mL) and the mixture was refluxe
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AlCl3, PhNO2 70 oC, 3 d H + Cl HO 6
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13.13.3.2.3 Method 3: Transformatio
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13.13.3.3.1.1.3 Method 3: Acylation
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o-3-nitropyridine in dimethyl sulfo
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13.13.3.3.1.1.8 Method 8: Alkylatio
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Scheme 242 Alkylation of 1H-Benzotr
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1H-benzotriazole derivatives are pr
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Scheme 250 Sulfonylation of Benzotr
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Scheme 253 Nitration of 1H-Benzotri
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13.13.3.3.2 Of Carbon Functionaliti
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Scheme 261 Deoxygenation of 1-Alkyl
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13.13.4.1.2 By Formation of One N-N
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Scheme 270 Synthesis of 2-Azidoazob
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13.13.4.1.2.1.3 Method 3: Cyclizati
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2-Methyl-6-nitro-2H-benzotriazole 1
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Scheme 282 Transformation of 1,3,3-
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Synthesis of 2H-Triazol-1-ium Salts
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Scheme 289 Alkylation of 1- and 2-S
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Scheme 294 Synthesis of Symmetrical
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References FOR PERSONAL USE ONLY Re
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FOR PERSONAL USE ONLY References 58
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Product Class 13: 1,2,3-Triazoles

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