formation:
1. bnezaldehyde -ZnCl2
2. benzaldehyde dimethyl acetal 3 eq.- TsOH 0.1 eq. in MeCN, refluxing. 2hr.
works great. >60% yield.
workup procedure:
remove mecn to about half invacuo, then NaHCO3 aq. solution added to quench TsOH. Further remove meCN completely invacuo.
EtOAc used to dissolve the product. wash with naHCO3,brine. then concentrated.
Add acetone to dissolve the solid. Add hexanes to precipitate the product. product collected by filtration.
(EtOAc is not a good solvent for the product, so have to use acetone, benzaldehyde dimethyl acetal can dissolve in hexanes).
the rxn is reversible, so base should be used to destroy the catalyst after done.
3. phCHBr2 -base
4. benzaldehyde dimethylacetal , I2 in MeCN ,rt. 1-2 hr.
although the author claimed more than 90% yield, I can only get about 30-40% yield after workup( Na2S2O3 quenching). the author also claimed a simple workup by vacuum away MeCN and I2, but removal of I2 by vacuum is really not practical.
removal:
1. MeOH, I2, reflux, 2 hr
works great, >80%
2. MeOH, TsOH, rt
Monday, January 26, 2009
Subscribe to:
Post Comments (Atom)
1 comment:
Physcion 8-β-D-glucoside has been studied in research relating to the treatment of the glomerulonephritis. It is the glucoside of Physcion (P398000) which is a natural anthraquinone derivative, on the infection process of Blumeria graminis on wheat. Physcion-8-O-β-D-glucopyranoside
Post a Comment