The Product of Catalysed Diboration of Bis(4-methoxyphenyl)ethyne by Bis(pinacolato-O,O')diboron

The title compound, (Z)-1,2-bis(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)- 1,2-bis(4-methoxyphenyl)ethene, C₂₈H₃₈B₂O₆, has a cis arrangement of two boronate ester substituents and two 4-methoxyphenyl substituents on its central C=C double bond, which shows a slight twist of ca 8.5°. All four substituents are rotated considerably out of the alkene plane to reduce steric hindrance. The BO₂C₂ five-membered rings have a twist conformation.

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