Glucal stannylated

D-glucal (10) and di-(tributyltin) oxide in dry benzene are refluxed using a Dean-Stark trap. Under these conditions stannyl complex 36 of the D-glucal is formed. Ogawa was the first to report on the stereoselective stannylation.12... 

To avoid stannyl reagents, there is the possibility to synthesize the same building block in one more step. First step is the formation of the benzylidene acetal 38 at the positions C-4 and C-6 of the glucal 10. The acetal formation at C-4 / C-6 is favored because you can get a six-membered instead of a five-membered ring at the position C-3 / C-4. To form 38 benzaldehyde dimethyl acetal 39 can be used with catalytic amounts of para-toluenesulfonic acid. 

Another approach developed by the Vogel group relies on a carbonylative Stille cross-coupling between stannylated glucal derivative 410 and enol triflate 412 derived from isolevoglucosenone [152] (O Scheme 80). 

In 1986, as the technology surrounding the preparation of C-disaccharides progressed, the use of metallated glycals, radical reactions, and dipolar cycloadditions began to be used. With respect to metallated glycals, extensively discussed in Chapter 3, Hanessian, etal.,9 stannylated the tri-O-silylated glucal... 

---