Dimethoxybenzoin Esters

Shi, Y Corrie, J.E.T. and Wan, P. (1997) Mechanism of 3, 5 -dimethoxybenzoin ester photochemistry heterolytic cleavage intramolecularly assisted by the dimefhoxybenzene ring is the primary photochemical step. Journal of Organic Chemistry, 62, 8278-8279. 

Givens58 and Pirrung59 used photolabile 3 3 -dimethoxybenzoin esters for the protection of phosphotriesters. A complication attending the use of racemic 3 5 dimethoxybenzoin is the generation of four diastereoisomers if the phosphate is chiral. An asymmetric synthesis of 3, 5 -dimethoxybenzoin 303 [Scheme 7.30] via the 0-trimethylsilyl-3,5-dimethoxybenzaldehyde cyanohydrin 303 minimises the number of diastereoisomers created in the phosphorylation of chiral alcohols. Thus reaction of 303 with 2 - cyanoethoxy)(NPNf-diisopropy amino)-chlorophosphine afforded the phosphoramidite 30.4 which then reacted with Boc-Ser-OMe to give the two diastereoisomeric phosphotriesters 303, Photode-... 

In 1994, Pirrung and Shuey ° reported the protection of phosphates using the dimethoxybenzoin. Resolved ( RjS S -dimethoxybenzoin (optically active) was converted to the phosphoramidite by treatment with diisopropylaminocyanoethoxychlorophosphine. Subsequent reaction with the appropriate primary or secondary alcohol followed by oxidation led to the series of phosphate esters 58a-e in moderate to high yields ... 

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