9-Borabicyclo[3.3.1]nonane dimer21205-91-4100 % similar Cyclobutylboronic acid849052-26-247 % similar 9-Methoxy-9-borabicyclo(3.3.1)nonane38050-71-440 % similar Cyclopentylboronic acid63076-51-739 % similar B-Cyclohexylboronic acid4441-56-937 % similar