Hydroboration/oxidation vs acid-catalyzed hydration of 1-phenylpropene
Hydroboration

With the simplest hydroborating agent $\ce{BH3.THF}$, the hydroboration/oxidation of 1-phenylpropene proceeds to give 1-phenylpropan-1-ol as the major product.[1] The isomer of the substrate used was not reported.



There is some ambiguity in the above source, as the labels 8 and 8′ (which the paper uses to refer to the two regioisomers) are consistently swapped; hence, I have taken the names and not the labels to be accurate. However, as additional proof, there are other examples of similar regioselectivity in the hydroboration of styrenes (here, an E/Z mixture of styrenes was used):[2]



Rationalising this selectivity is not very easy, but in one of Herbert Brown's papers where the same regioselectivity is seen with 9-BBN as the hydroborating agent, he writes:[3]


  The preferred site of hydroboration in 1-phenylpropene, the site to which boron becomes attached, is the 1-position. This is not what one would expect on the basis of steric effects. One possible explanation for this is the combined effects of phenyl conjugation (-K) and methyl hyperconjugation (+K) which act to decrease the amount of electron density at the 2-position and to increase it at the 1-position.


I'm not totally convinced by this, but I also don't have any better explanation. Further evidence for this explanation is the fact that the (Z)-isomer reacts with poorer regioselectivity than the (E)-isomer. This is because there is allylic strain in the (Z)-isomer which forces the phenyl group to twist out of conjugation with the C=C double bond (depicted below). Consequently, the electron-withdrawing effect of the benzene ring (via conjugation) is reduced, and the formation of the 2-hydroxy isomer is less disfavoured.





Acid-catalysed hydration

Examples of these in the literature are harder to find and I cannot find any generic examples of acidic hydration of $\ce{R^{1}-C=C-R^{2}}$, where $\ce{R^1}$ is an aryl group and $\ce{R^2}$ an alkyl. However, I see no particular reason to go against the conventional wisdom: the more stable carbocation intermediate is formed at the benzylic position, which should lead to the 1-hydroxy compound as the major product.



References


Camacho, C.; Uribe, G.; Contreras, R. Diphenylamine Borane, A New Stable Amine .Borane with Remarkable Hydroborating and Reducing Properties. Synthesis 1982, 1982 (12), 1027–1030. DOI: 10.1055/s-1982-30051.
Allegretti, M.; Bertini, R.; Cesta, M. C.; Bizzarri, C.; Di Bitondo, R.; Di Cioccio, V.; Galliera, E.; Berdini, V.; Topai, A.; Zampella, G.; Russo, V.; Di Bello, N.; Nano, G.; Nicolini, L.; Locati, M.; Fantucci, P.; Florio, S.; Colotta, F. 2-Arylpropionic CXC Chemokine Receptor 1 (CXCR1) Ligands as Novel Noncompetitive CXCL8 Inhibitors. J. Med. Chem. 2005, 48 (13), 4312–4331. DOI: 10.1021/jm049082i.
Brown, H. C.; Nelson, D. J.; Scouten, C. G. Hydroboration. 63. Kinetics and regiospecificity of the hydroboration of isomeric cis- and trans-alkenes via 9-borabicyclo[3.3.1]nonane (9-BBN). Effects of 1,1- and 1,2-dialkyl interactions. J. Org. Chem. 1983, 48 (5), 641–643. DOI: 10.1021/jo00153a003.