[carotis]

Hey there!

Need your opinion. How much of a gain will I receive when I follow these synthesis steps?

1) Benzaldehyde reacts with NaCN as katalysator and ethanol as solvent to Benzoin:

C6H5-COH => Benzoin

2) Hydroboration  of Benzoin probably delivers the Hydrobenzoin:
Bezoin + (NaBH4) => Hydrobenzoine


Which methods of synthezising HYdrobenzoin do you know, which are the easiest one and which one gives mainly cis-products?

[phth]

what do you mean by cis? Formation of the condensation product is formation of a chiral center not an alkene. http://www.organic-chemistry.org/namedreactions/pinacol-coupling-reaction.shtm

[carotis]

well there are cis and trans products, isn't it?

[discodermolide]

Cis and trans refer to the stereochemistry around a C=C. As far as I can glean from your post you do a borohydride reduction of benzoin. This provides a 1,2-diol. So what is the stereochemistry of this product?