Reaction #67591

Reaction equation

5-(3,3-dimethyl-but-1-ynyl)-3-iodo-thiophene-2-carboxylic acid methyl ester

N-methyl-N-pyridin-2-yl-hydrazine

K2CO3

→

5-(3,3-dimethyl-but-1-ynyl)-3-(N′-methyl-N′-pyridin-2-yl-hydrazino)-thiophene-2-carboxylic acid methyl ester

Yield 50.0%

Solvents

ethyl acetate

DMF

Conditions

Workup

1. 1
   Washwashed twice with 5% LiCl
2. 2
   Concentrationconcentrated
3. 3
   Otherthe crude material was purified by silica gel chromatography (0-20% EtOH in DCM)

Procedure

A mixture of 5-(3,3-dimethyl-but-1-ynyl)-3-iodo-thiophene-2-carboxylic acid methyl ester (0.100 g, 0.28 mmol), N,N-diethylenediamine (9 μL, 0.086 mmol), N-methyl-N-pyridin-2-yl-hydrazine (0.105 g, 0.86 mmol), CuI (0.01 g, 0.057 mmol), 4 Å ms (0.114 mg) and K2CO3 (0.118 g, 0.861 mmol) in DMF (3 mL) was heated to 80° C. for 16 h. The reaction was diluted with ethyl acetate, washed twice with 5% LiCl, concentrated and the crude material was purified by silica gel chromatography (0-20% EtOH in DCM) to give 5-(3,3-dimethyl-but-1-ynyl)-3-(N′-methyl-N′-pyridin-2-yl-hydrazino)-thiophene-2-carboxylic acid methyl ester in 50% yield. This was then dissolved in pyridine (5 mL) and treated with neat trans-4-methyl-cyclohexanecarbonyl chloride (0.132 g, 0.825 mmol). The reaction was heated for 16 h at 85° C. and quenched with saturated ammonium chloride solution. The reaction mixture was diluted with EtOAc, washed with water, brine, dried over sodium sulfate, filtered and concentrated. The crude material was then dissolved in a 3:2:1 mixture of THF:MeOH:water (5 mL), treated with lithium hydroxide monohydrate (0.69 g, 1.65 mmol) and heated to 60° C. for 1 hour. The organic volatiles were evaporated under reduced pressure and the crude material was purified by HPLC to afford the title compound. MS (m/z): 454.1 [M+H]−; HPLC retention time: 3.95 min (2-98% acetonitrile:water with 0.05% trifluoroacetic acid).

Source