I am only aware of lithium-halogen exchange protocols and Hartwig-type borylations (requiring expensive noble metals). You could add methyllithium to trimethyl borate, or phenyllithium to trimethyl borate, then workup with AcOH, but the best option is to buy methyl boronic acid and phenylboronic acid.

http://www.sigmaaldrich.com/catalog/product/aldrich/165336?lang=en®ion=CA

http://www.sigmaaldrich.com/catalog/product/aldrich/p20009?lang=en®ion=CA

You can hydroborate phenylacetylene with pinacolatoborane then hydrolyse to obtain the E-phenylethenyl boronic acid.

Lindlar reduction of TMS phenylacetylene gives the Z-silyl group which can be converted to the vinyl bromide with NBS, subsequent Li-hal exchange and quench with dimethylborate should afford the Z-phenylethenyl boronic acid.

Manas Jyoti Sarma,

                                              There are variety of  synthetic protocols available for the preparation of the organic boronic acids. The choice of the reactions like lithiation of bromoarene or bromoalkane, followed by the treatment with alkoxyborane (nucleophillic substitution reaction), is always best one. The yield is also promising.

If you don't want to use reactive alkyllithium for the lithiation reaction. I would like to suggest to prepare Grignard reagent from iodomethane and bromo/iodo benzene, followed by the the treatment with trialokoxy borane. The yield of the reaction, in the cases you describe, will be reasonable.