(4-Pentylphenyl)boronic acid → 3,4-Difluoro-4'-pentylbiphenyl-2-carbaldehyde

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Reaction Steps

2-bromo-5,6-difluorobenzaldehyde is reacted with 4-pentylphenylboronic acid in the presence of a Pd catalyst to give 3,4-difluoro-4′-pentylbiphenyl-2-carbaldehyde. This compound is reacted with trimethylsulfonium iodide, to give 3,4-difluoro-2-(oxiran-2-yl)-4′-pentyl-biphenyl. Without further purification, this compound is converted into 1,2-difluoro-7-pentylphenanthrene in the presence of BF3 etherate. The raw product is purified by the procedure typical for this type of liquid-crystal materials (cf. DE-A 195 00 768), yielding 1,2-difluoro-7-pentylphenanthrene in the form of colorless crystals. Kumar, J. Org. Chem. 1997, 62, 8535-8539 discloses the coupling of boronic acid compounds with a bromo compound having aldehyde functionality.

Provenance & Evidence