Yield:70260-05-8 78%

Reaction Conditions:

with borane-THF in tetrahydrofuran at 0 - 20; for 2.5 h;

Steps:

100.1 Preparation of 90 Step 1: (4-Bromo-thiophen-3-yl)-methanol

To a solution of 4-bromothiophene-3-carboxylic acid (3.6 g, 17 mmol) in anhydrous tetrahydrofuran at 0° C. was added a tetrahydrofuran solution (Aldrich, 1 M) of BH₃.tetrahydrofuran (243 mL, 0.24 mol). The reaction mixture was stirred at 0° C. for 0.5 h, then at room temperature for 2 h. The mixture was concentrated, and the residue was partitioned between ethyl acetate and aqueous dilute HCl solution. The organic layer was separated, and the aqueous layer was extracted with ethyl acetate. The combined organic extract was washed with saturated NaHCO₃ solution and brine, and then dried over MgSO₄, and concentrated. The residue was purified by chromatography (10-50% ethyl acetate in hexanes) to give the product ( 90) as a colorless oil (2.6 g, 78%).

References:

US2014/194431,2014,A1 Location in patent:Paragraph 0471-0472