Yield:-

Reaction Conditions:

Stage #1: methyl 4,5-dibromothiophene-3-carboxylatewith diisobutylaluminium hydride in dichloromethane;toluene at -78 - 20; for 2.67 h;
Stage #2: with rochelle salt in methanol;dichloromethane;water;toluene;

Steps:

3.a

Step (a): Methyl 4,5-dibromothiophene~3-carboxylate (3.34 mmol, 3 .00 g) was dissolved in DCM (25 ml.) and cooled to -78 °C. DIBAL-H (4.18 rnL of IM solution in toluene, 4.18 mmol,) was slowly added over 1 rnin and the mixture was then stirred at -78 °C for 60 min. The cooling bath was removed and the reaction was stirred at room temp for 90 min. 3 ml, MeOH were added, followed by 30 nil, of Roeheiie- salt solution (5% w/w in j?0). The mixture was stirred until a clear solution, was obtained. The phases were separated and the organic phase was dried with Mg₂SQ₄ and the solvent was evaporated. The crude product (4.5-dibroniothiophen-3-yi)methanol (883 mg) was used without further purification in the next step.

References:

WO2012/22776,2012,A1 Location in patent:Page/Page column 27-28