Encyclopedia

  • Kinetic cyclohexylidenation and isopropylidenation of aldose diethyl dithioacetals
  • Add time:07/21/2019         Source:sciencedirect.com

    Aldose diethyl dithioacetals react with 1.2 equivalents of 1-ethoxycyclohexene or 2-methoxypropene in N,N-dimethylformamide at 0° with p-toluenesulfonic acid as catalyst to give the five-membered ring acetal attached to the two terminal oxygen atoms as the major product in every case. In most instances, a small proportion of the terminal, six-membered ring acetal was also obtained, and in a few cases, terminal seven-membered ring acetals were also isolated. Cyclohexylidenation at room temperature gave the same products, but isopropyl-idenation at room temperature resulted in certain cases in partial rearrangement. Cyclohexylidenation reactions gave smaller proportions of the minor six- and seven-membered ring products. Structures were established from 13C-n.m.r. and mass spectra. The 13C-n.m.r. spectra of model cyclohexylidene derivatives were found very similar to those of isopropylidene derivatives previously studied. Two new features useful for structure determination were noted when the spectra of the precursor diols were compared with those of both types of derived acetals; the chemical shift of C-2 of a 1,3-propanediol derivative was shifted upfield by 6–9 p.p.m. on acetalation and the shifts of the diol carbon atoms attached to oxygen were affected according to the type of acetal and ring-size formed. Similar observations were made for methylene acetals.

    We also recommend Trading Suppliers and Manufacturers of Acetone diethyl dithioacetal (cas 14252-45-0). Pls Click Website Link as below: cas 14252-45-0 suppliers


    Prev:Facile deprotection of dithioacetals by using a novel 1,4-benzoquinone/cat. NaI system
    Next: Rapid gas chromatographic of partially methylated aldoses as trimethylsilylated diethyl dithioacetals)

About|Contact|Cas|Product Name|Molecular|Country|Encyclopedia

Message|New Cas|MSDS|Service|Advertisement|CAS DataBase|Article Data|Manufacturers | Chemical Catalog

©2008 LookChem.com,License: ICP

NO.:Zhejiang16009103

complaints:service@lookchem.com Desktop View