Azzindani/Open_Reaction_Data huggingface dataset:
Reaction SMILES: C(O)C.[CH:4]1([C:10]2[C:18]3[C:17](=[O:19])[NH:16][C:15]([C:20]4[CH:25]=[CH:24][C:23]([N:26]5[CH2:31][CH2:30][C:29](=[O:32])[CH2:28][CH2:27]5)=[CH:22][C:21]=4[O:33][CH3:34])=[N:14][C:13]=3[N:12]([CH3:35])[N:11]=2)[CH2:9][CH2:8][CH2:7][CH2:6][CH2:5]1.[BH4-].[Na+]>CC(C)=O>[CH:4]1([C:10]2[C:18]3[C:17](=[O:19])[NH:16][C:15]([C:20]4[CH:25]=[CH:24][C:23]([N:26]5[CH2:31][CH2:30][CH:29]([OH:32])[CH2:28][CH2:27]5)=[CH:22][C:21]=4[O:33][CH3:34])=[N:14][C:13]=3[N:12]([CH3:35])[N:11]=2)[CH2:5][CH2:6][CH2:7][CH2:8][CH2:9]1
Reactant: COc1cc(N2CCC(=O)CC2)ccc1-c1nc2c(c(C3CCCCC3)nn2C)c(=O)[nH]1
Agent: [BH4-]
Agent: [Na+]
Solvent: CC(C)=O
Solvent: CCO
Product: COc1cc(N2CCC(O)CC2)ccc1-c1nc2c(c(C3CCCCC3)nn2C)c(=O)[nH]1
Temperature: 25 °C
Reaction time: 1.5 h
Yield: 77.4 %

Procedure:
To a 30 ml ethanol suspension of 780 mg (1.79 mmol) of the compound obtained in Example 30, 81 mg (2.15 mmol) of sodium borohydride was added, and the mixture was stirred at room temperature for 1.5 hours. Then, acetone was added to the reaction mixture, and the mixture was concentrated under reduced pressure. Water was added to the residue, and the mixture was extracted with methylene chloride. The organic layer was washed with water and a saturated aqueous solution of sodium chloride in this order. Then, the washed layer was dried over anhydrous sodium sulfate, and then the solvent was distilled off under reduced pressure. The residue was purified by silica gel column chromatography (chloroform/methanol=40/1) to obtain 606 mg (77%) of the captioned compound.
Reaction SMILES: [CH2:1]([S:3]([N:6]1[CH2:11][CH2:10][CH:9]([C:12]2[C:20]3[C:15](=[C:16]([C:28]([NH2:30])=[O:29])[CH:17]=[C:18]([C:21]4[CH:25]=[C:24]([CH:26]=O)[S:23][CH:22]=4)[CH:19]=3)[NH:14][CH:13]=2)[CH2:8][CH2:7]1)(=[O:5])=[O:4])[CH3:2].C[N:32]1[CH2:36][CH2:35][CH2:34][C@@H:33]1[CH3:37].C(O[BH-](OC(=O)C)OC(=O)C)(=O)C.[Na+]>CS(C)=O.C(O)(=O)C>[CH2:1]([S:3]([N:6]1[CH2:11][CH2:10][CH:9]([C:12]2[C:20]3[C:15](=[C:16]([C:28]([NH2:30])=[O:29])[CH:17]=[C:18]([C:21]4[CH:25]=[C:24]([CH2:26][N:32]5[CH2:36][CH2:35][CH2:34][C@@H:33]5[CH3:37])[S:23][CH:22]=4)[CH:19]=3)[NH:14][CH:13]=2)[CH2:8][CH2:7]1)(=[O:4])=[O:5])[CH3:2]
Reactant: CCS(=O)(=O)N1CCC(c2c[nH]c3c(C(N)=O)cc(-c4csc(C=O)c4)cc23)CC1
Reactant: C[C@H]1CCCN1C
Agent: CC(=O)O[BH-](OC(C)=O)OC(C)=O
Agent: [Na+]
Solvent: CC(=O)O
Solvent: CS(C)=O
Product: CCS(=O)(=O)N1CCC(c2c[nH]c3c(C(N)=O)cc(-c4csc(CN5CCC[C@@H]5C)c4)cc23)CC1
Temperature: 25 °C
Reaction time: 6 h
Yield: 17.3 %

Procedure:
To a solution of 3-[1-(ethylsulfonyl)-4-piperidinyl]-5-(5-formyl-3-thienyl)-1H-indole-7-carboxamide (600 mg, 1.348 mmol) in dimethyl sulfoxide (10 mL) was added of 20 drops of acetic acid and (2S)-1,2-dimethylpyrrolidine (1.37 mL, 13.483 mmol). The resulting mixture was stirred at room temperature for 6 h followed by an addition of sodium triacetoxyborohydride (2.858 g, 13.483 mmol). The reaction was stirred at room temperature overnight then purified by SFC. This compound was separated by RTP CASS Group. The fraction of enantiomer #1 is 99.7% chirally pure to give 119.9 mg of the title compound (17.3%).
Reaction SMILES: N(C(OCC)=O)=NC(OCC)=O.[CH3:13][N:14]([CH2:16][CH:17]1[CH2:26][CH2:25][C:24]2[C:19](=[CH:20][CH:21]=[C:22]([OH:27])[CH:23]=2)[CH2:18]1)[CH3:15].[CH3:28][O:29][C:30]1[CH:45]=[CH:44][C:33]([CH2:34][O:35][C:36]2[CH:43]=[CH:42][C:39]([CH2:40]O)=[CH:38][CH:37]=2)=[CH:32][CH:31]=1.C1(P(C2C=CC=CC=2)C2C=CC=CC=2)C=CC=CC=1>C1COCC1>[CH3:15][N:14]([CH2:16][CH:17]1[CH2:26][CH2:25][C:24]2[C:19](=[CH:20][CH:21]=[C:22]([O:27][CH2:40][C:39]3[CH:42]=[CH:43][C:36]([O:35][CH2:34][C:33]4[CH:32]=[CH:31][C:30]([O:29][CH3:28])=[CH:45][CH:44]=4)=[CH:37][CH:38]=3)[CH:23]=2)[CH2:18]1)[CH3:13]
Reactant: COc1ccc(COc2ccc(CO)cc2)cc1
Reactant: CN(C)CC1CCc2cc(O)ccc2C1
Agent: CCOC(=O)N=NC(=O)OCC
Agent: c1ccc(P(c2ccccc2)c2ccccc2)cc1
Solvent: C1CCOC1
Product: COc1ccc(COc2ccc(COc3ccc4c(c3)CCC(CN(C)C)C4)cc2)cc1
Reaction time: 12 h
Yield: 41.2 %

Procedure:
Diethyl azodicarboxylate (40% toluene solution, 1.91 g) was added dropwise to THF solution (6 ml) of 2-[(N,N-dimethylamino)methyl]-6-hydroxytetralin (300 mg), 4-[(4-methoxybenzyl)oxy]benzylalcohol (1.07 g) and triphenylphosphine (1.15 g) at room temperature, which was stirred for 12 hours. The reaction mixture was concentrated, and the residue was purified using alumina column chromatography (development solvent; hexane˜hexane:ethyl acetate=10:1), and recrystallized (ethyl acetate-hexane) to give the titled compound (260 mg).
Reaction SMILES: [C:1]1(=[O:7])[O:6][C:4](=[O:5])[CH2:3][CH2:2]1.[C:8]([O:12][CH2:13][CH2:14][OH:15])(=[O:11])[CH:9]=[CH2:10].C(C1C=C(C)C=C(C(C)(C)C)C=1O)(C)(C)C>[Cl-].C[N+](C)(C)C>[C:8]([O:12][CH2:13][CH2:14][O:15][C:4]([CH2:3][CH2:2][C:1]([OH:6])=[O:7])=[O:5])(=[O:11])[CH:9]=[CH2:10]
Reactant: C=CC(=O)OCCO
Reactant: O=C1CCC(=O)O1
Agent: C[N+](C)(C)C
Agent: Cc1cc(C(C)(C)C)c(O)c(C(C)(C)C)c1
Agent: [Cl-]
Product: C=CC(=O)OCCOC(=O)CCC(=O)O
Temperature: 90 °C

Procedure:
A mixture of succinic anhydride (30.0 g), 2-hydroxyethyl acrylate (34.2 g), tetramethylammonium chloride (0.2 g), and 2,6-di-tert. butyl-4-methyl phenol (0.15 g) is heated at 90° C. for 3 hours, by which time the infra-red spectrum of the mixture shows that almost all of the anhydride has reacted. The mixture is cooled to give the desired acid.
Reaction SMILES: [N+](C1C=CC(CNC(N)=O)=CC=1)([O-])=[O:2].[NH2:15][C:16]1[N:21]([CH2:22][C:23]2[CH:28]=[CH:27][C:26]([N+:29]([O-])=O)=[CH:25][CH:24]=2)[C:20](=[O:32])[N:19]([CH3:33])[C:18](=[O:34])[CH:17]=1.[Cl-].[Ca+2].[Cl-]>O.C(O)(=O)C.[Zn]>[C:18]([OH:34])(=[O:2])[CH3:17].[NH2:15][C:16]1[N:21]([CH2:22][C:23]2[CH:28]=[CH:27][C:26]([NH2:29])=[CH:25][CH:24]=2)[C:20](=[O:32])[N:19]([CH3:33])[C:18](=[O:34])[CH:17]=1
Reactant: Cn1c(=O)cc(N)n(Cc2ccc([N+](=O)[O-])cc2)c1=O
Reactant: NC(=O)NCc1ccc([N+](=O)[O-])cc1
Agent: [Ca+2]
Agent: [Cl-]
Agent: [Zn]
Solvent: O
Solvent: CC(=O)O
Product: Cn1c(=O)cc(N)n(Cc2ccc(N)cc2)c1=O
Temperature: 25 °C
Reaction time: 1.5 h

Procedure:
Using the general procedure for Intermediate 1, (4-nitro-benzyl)-urea [J. Med. Chem. 1996, 39, 1924] is converted into 6-amino-3-methyl-1-(4-nitro-benzyl)-1H-pyrimidin-2,4-dione, [MH]+ 277. A solution of calcium chloride (4.94 g, 45 mmol) in water (100 ml) is added to a solution of 6-amino-3-methyl-1-(4-nitro-benzyl)-1H-pyrimidine-2,4-dione (19.08 g, 69.0 mmol) in acetic acid (300 ml). Zinc dust (58.8 g, 900 mmol) is then added portionwise with external cooling. The reaction is stirred at room temperature for 1.5 hours, filtered through a celite plug and washed successively with ethanol and acetic acid. Evaporation of the combined filtrate and washings affords 6-amino-1-(4-amino-benzyl)-3-methyl-1H-pyrimidin-2,4-dione acetic acid salt, [M-3H]− 243. Acetic anhydride (7.2 ml, 76.0 mmol) is added to a cooled (0° C.) suspension of 6-amino-1-(4-amino-benzyl)-3-methyl-1H-pyrimidine-2,4-dione acetic acid salt (17.0 g, 69.0mmol) in pyridine (260 ml). The reaction mixture is warmed to room temperature, stirred for 6 hours and the solvent evaporated. The residue is triturated with water and the solid collected by filtration and dried to afford N-[4-(6-amino-3-methyl-2,4-dioxo-3,4-dihydro-2H-pyrimidin-1-ylmethyl)-phenyl]-acetamide, [MH]+ 289. Using the general procedure for Intermediate 1, this compound is converted into N-[4-(5,6-diamino-3-methyl-2,4-dioxo-3,4dihydro-2H-pyrimidin-1-ylmethyl)-phenyl]-acetamide, [MH]+ 304.
Reaction SMILES: [CH2:1]([C:4]1[C:9]([F:10])=[C:8]([F:11])[C:7](F)=[C:6]([F:13])[C:5]=1[F:14])[CH:2]=[CH2:3].O.[NH2:16][NH2:17]>C(O)C>[CH2:1]([C:4]1[C:9]([F:10])=[C:8]([F:11])[C:7]([NH:16][NH2:17])=[C:6]([F:13])[C:5]=1[F:14])[CH:2]=[CH2:3]
Reactant: C=CCc1c(F)c(F)c(F)c(F)c1F
Reactant: NN
Solvent: O
Solvent: CCO
Product: C=CCc1c(F)c(F)c(NN)c(F)c1F

Procedure:
Allylpentafluorobenzene [41.6 g; described by Harper et al, J. Org. Chem., 29, 2385 (1964)] was added to a solution of hydrazine hydrate (100 ml) in ethanol (150 ml) and the mixture was heated at reflux for 24 hours. The solid precipitate which formed was collected by filtration and washed with ethanol and hexane to give 4-allyl-2,3,5,6-tetrafluorophenylhydrazine (18.8 g), m.p. 82°-84° C., in the form of colourless crystals. The filtrate was evaporated to dryness and the yellow solid thus obtained was washed with ethanol and hexane to give a further quantity (22.0 g) of 4-allyl-2,3,5,6-tetrafluorophenylhydrazine, m.p. 79°-81° C., in the form of a cream-coloured solid.
Reaction SMILES: C[N:2](C)/[CH:3]=[CH:4]/[C:5]([C:7]1[C:12](=[O:13])[CH:11]=[CH:10][N:9]([C:14]2[CH:19]=[CH:18][CH:17]=[C:16]([S:20]([CH3:23])(=[O:22])=[O:21])[CH:15]=2)[N:8]=1)=O.[NH:25]([C:27]1[CH:35]=[CH:34][C:30]([C:31]([OH:33])=[O:32])=[CH:29][CH:28]=1)N>>[CH3:23][S:20]([C:16]1[CH:15]=[C:14]([N:9]2[CH:10]=[CH:11][C:12](=[O:13])[C:7]([C:5]3[N:25]([C:27]4[CH:35]=[CH:34][C:30]([C:31]([OH:33])=[O:32])=[CH:29][CH:28]=4)[N:2]=[CH:3][CH:4]=3)=[N:8]2)[CH:19]=[CH:18][CH:17]=1)(=[O:22])=[O:21]
Reactant: CN(C)/C=C/C(=O)c1nn(-c2cccc(S(C)(=O)=O)c2)ccc1=O
Reactant: NNc1ccc(C(=O)O)cc1
Product: CS(=O)(=O)c1cccc(-n2ccc(=O)c(-c3ccnn3-c3ccc(C(=O)O)cc3)n2)c1

Procedure:
Reaction of 3-((E)-3-dimethylamino-acryloyl)-1-(3-methansulfonyl-phenyl)-1H-pyridazin-4-one (A-7) and 4-hydrazino-benzoic acid according to example 43 gave the desired product. MS: M=437.0 (M+H)+
Reaction SMILES: CC(OC([N:8]1[CH2:13][CH2:12][C:11]2([C:21]3[C:16](=[CH:17][CH:18]=[CH:19][CH:20]=3)[C:15]([C:22]3[CH:27]=[CH:26][CH:25]=[CH:24][N:23]=3)=[CH:14]2)[CH2:10][CH2:9]1)=O)(C)C.Cl.[CH3:29][C:30]([CH3:49])([O:32][C:33]([NH:35][C@H:36]([CH2:40][CH2:41][CH2:42][C:43]1[CH:48]=[CH:47][CH:46]=[CH:45][CH:44]=1)[C:37]([OH:39])=O)=[O:34])[CH3:31].C(Cl)CCl.C1C=CC2N(O)N=NC=2C=1.CN1CCOCC1>>[CH3:49][C:30]([O:32][C:33](=[O:34])[NH:35][CH:36]([C:37]([N:8]1[CH2:9][CH2:10][C:11]2([C:21]3[C:16](=[CH:17][CH:18]=[CH:19][CH:20]=3)[C:15]([C:22]3[CH:27]=[CH:26][CH:25]=[CH:24][N:23]=3)=[CH:14]2)[CH2:12][CH2:13]1)=[O:39])[CH2:40][CH2:41][CH2:42][C:43]1[CH:48]=[CH:47][CH:46]=[CH:45][CH:44]=1)([CH3:29])[CH3:31]
Reactant: CC(C)(C)OC(=O)N[C@H](CCCc1ccccc1)C(=O)O
Reactant: CC(C)(C)OC(=O)N1CCC2(C=C(c3ccccn3)c3ccccc32)CC1
Agent: Cl
Agent: On1nnc2ccccc21
Solvent: CN1CCOCC1
Solvent: ClCCCl
Product: CC(C)(C)OC(=O)NC(CCCc1ccccc1)C(=O)N1CCC2(C=C(c3ccccn3)c3ccccc32)CC1
Yield: 69.7 %

Procedure:
The intermediate from Step A (120 mg, 0.33 1 mmol) was treated with 4N HCl as in Example 85, Step A. The residue was reacted with the compound prepared in Example 73, Step B (97 mg, 0.33 mmol), EDC (94.7 mg. 0.496 mmol), HOBT (67 mg, 0.49 mmol) and NMM (0.076 ml, 0.66 mmol) according to the procedure described for Example 1, Step A. The title compound (123 mg, 0.23 mmol) was obtained as a white solid after flash chromatography.
Reaction SMILES: [NH:1]1[C:5]2=[N:6][CH:7]=[CH:8][CH:9]=[C:4]2[CH:3]=[CH:2]1.C([O-])(O)=[O:11].[Na+].OOS([O-])=O.[K+]>CO.O>[NH:1]1[C:5]2=[N+:6]([O-:11])[CH:7]=[CH:8][CH:9]=[C:4]2[CH:3]=[CH:2]1
Reactant: O=C([O-])O
Reactant: c1cnc2[nH]ccc2c1
Agent: O=S([O-])OO
Agent: [K+]
Agent: [Na+]
Solvent: O
Solvent: CO
Product: [O-][n+]1cccc2cc[nH]c21
Temperature: 25 °C
Reaction time: 5 h

Procedure:
To a suspension of 1H-pyrrolo[2,3-b]pyridine (10.0 g) and NaHCO3 (45.2 g) in 1:1 MeOH/H2O (1000 mL) was added Oxone® (106 g) in potions during 40 min period. The mixture was stirred at RT for 5 h. The sold was removed by filtration and the filtrate was concentrated to 200 mL in volume. This aqueous phase was extracted with CH2Cl2 (200 mL×7) to afford 1H-pyrrolo[2,3-b]pyridine 7-oxide.
Reaction SMILES: [CH:1]1([C:4]2[CH:9]=[CH:8][CH:7]=[CH:6][CH:5]=2)[CH2:3][CH2:2]1.C([O-])(=O)C.[Na+].[Br:15]Br.OS([O-])=O.[Na+]>C(O)(=O)C.O>[CH:1]1([C:4]2[CH:9]=[CH:8][C:7]([Br:15])=[CH:6][CH:5]=2)[CH2:3][CH2:2]1
Reactant: c1ccc(C2CC2)cc1
Reactant: BrBr
Agent: CC(=O)[O-]
Agent: O=S([O-])O
Agent: [Na+]
Solvent: O
Solvent: CC(=O)O
Product: Brc1ccc(C2CC2)cc1
Temperature: 25 °C
Reaction time: 5 h
Yield: 21 %

Procedure:
Cyclopropyl benzene (48.5 g, 410 mmol), glacial acetic acid (510 mL), and sodium acetate (38.9 g, 474 mmol) were added to a roundbottomed flask. The flask was cooled in an ice-water bath. A solution of bromine (66.3 g, 414 mmol) dissolved in 105 mL of acetic acid was added dropwise over 90.min. The reaction mixture was stirred at temperatures between 0° C. and 10° C. for 5 h. The reaction was then allowed to warm to rt overnight. Hexanes (1300 mL) and water (250 mL) were added. Aqueous NaHSO3 (1 M) was added until the reaction mixture changed from yellow to clear. The layers were separated. The organic layer was washed with water, 1M aq Na2CO3, and brine, then dried with Na2SO4. The solvent was evaporated and the crude product was purified via sgc using hexanes as the mobile phase to give 17 g of p-cyclopropylbromobenzene (21%) (Compound 44).
Reaction SMILES: [S:1]([O-:5])([O-:4])(=[O:3])=[S:2].[Na+:6].[Na+].[I-].[Na+].Cl[CH2:11][CH2:12][N:13]1[C:22]2[C:17](=[CH:18][CH:19]=[C:20]([CH3:23])[CH:21]=2)[CH:16]([CH3:24])[CH2:15][C:14]1([CH3:26])[CH3:25].O>C(O)C>[S:1]([O-:5])([S:2][CH2:11][CH2:12][N:13]1[C:22]2[C:17](=[CH:18][CH:19]=[C:20]([CH3:23])[CH:21]=2)[CH:16]([CH3:24])[CH2:15][C:14]1([CH3:25])[CH3:26])(=[O:4])=[O:3].[Na+:6]
Reactant: O=S([O-])([O-])=S
Reactant: Cc1ccc2c(c1)N(CCCl)C(C)(C)CC2C
Agent: [I-]
Agent: [Na+]
Solvent: O
Solvent: CCO
Product: Cc1ccc2c(c1)N(CCSS(=O)(=O)[O-])C(C)(C)CC2C

Procedure:
A mixture of sodium thiosulfate (49.6 g, 0.2 m), sodium iodide (1 g), N-(2-chloroethyl)-2,2,4,7-tetramethyl-1,2,3,4-tetrahydroquinoline (25.2 g, 0.1 m), water (100 ml), and ethanol (100 ml) was refluxed fro 3 hrs. The mixture was cooled and extracted with 2-75 ml portions of toluene. The aqueous layer then contained essentially pure product and aliquots were used to prepare dyes without further purification.
Reaction SMILES: Cl[C:2]1[C:3]([N+:19]([O-:21])=[O:20])=[CH:4][C:5]([CH3:18])=[C:6]([NH:8][C:9](=[O:17])[CH2:10][C:11]2[CH:16]=[CH:15][CH:14]=[CH:13][CH:12]=2)[CH:7]=1.[SH:22][C:23]1[CH:28]=[CH:27][C:26]([OH:29])=[CH:25][CH:24]=1.C(=O)([O-])[O-].[Cs+].[Cs+]>CN(C)C=O>[OH:29][C:26]1[CH:27]=[CH:28][C:23]([S:22][C:2]2[C:3]([N+:19]([O-:21])=[O:20])=[CH:4][C:5]([CH3:18])=[C:6]([NH:8][C:9](=[O:17])[CH2:10][C:11]3[CH:16]=[CH:15][CH:14]=[CH:13][CH:12]=3)[CH:7]=2)=[CH:24][CH:25]=1
Reactant: Cc1cc([N+](=O)[O-])c(Cl)cc1NC(=O)Cc1ccccc1
Reactant: Oc1ccc(S)cc1
Agent: O=C([O-])[O-]
Agent: [Cs+]
Solvent: CN(C)C=O
Product: Cc1cc([N+](=O)[O-])c(Sc2ccc(O)cc2)cc1NC(=O)Cc1ccccc1
Temperature: 25 °C
Yield: 71.5 %

Procedure:
The product from Example 265A (0.305 g, 1.0 mmol), 4-mercaptophenol (0.151 g, 1.2 mmol, 1.2 eq) and cesium carbonate (0.782 g, 2.4 mmol, 2.4 eq) in dimethyl formamide (10 mL) was heated at 110° C. for 2 h, cooled to room temperature, and poured over ice water (100 mL). This mixture was extracted with ethyl acetate (3×150 mL) and the combined organic phases were washed with saturated aqueous sodium chloride, dried over anhydrous magnesium sulfate, filtered, and evaporated. The residue was purified by chromatography on silica gel eluting with 1:1 hexane/ethyl acetate to provide the title compound as a yellow solid (0.282 g, 72%).
Reaction SMILES: [C:1]1([CH3:11])[CH:6]=[CH:5][C:4]([S:7](Cl)(=[O:9])=[O:8])=[CH:3][CH:2]=1.[C:12]1([CH2:18][CH2:19][CH2:20][CH2:21][CH2:22][CH2:23][CH2:24][CH2:25][CH2:26][CH2:27][CH2:28][OH:29])[CH:17]=[CH:16][CH:15]=[CH:14][CH:13]=1>N1C=CC=CC=1>[S:7]([O:29][CH2:28][CH2:27][CH2:26][CH2:25][CH2:24][CH2:23][CH2:22][CH2:21][CH2:20][CH2:19][CH2:18][C:12]1[CH:13]=[CH:14][CH:15]=[CH:16][CH:17]=1)([C:4]1[CH:5]=[CH:6][C:1]([CH3:11])=[CH:2][CH:3]=1)(=[O:9])=[O:8]
Reactant: OCCCCCCCCCCCc1ccccc1
Reactant: Cc1ccc(S(=O)(=O)Cl)cc1
Solvent: c1ccncc1
Product: Cc1ccc(S(=O)(=O)OCCCCCCCCCCCc2ccccc2)cc1
Reaction time: 16 h

Procedure:
4-Toluenesulphonyl chloride (2.6 g) was added in portions to a stirred solution of the product of step (a) (2.9 g) in pyridine (10 ml) at 0° C. The solution was stirred for 16 hours at 0°-5° C. then poured onto ice-hydrochloric acid and extracted with ether. The extract was washed with sodium bicarbonate and sodium chloride solutions, dried and evaporated. The residue was chromatographed on silica gel eluting with 1:1 dichloromethane:hexane to give the title compound as a colourless oil.