The steric course of some reactions of 2,3-dihalotetrahydropyrans with sodium methoxide and with methyl- and phenyl-magnesium bromides has been reinvestigated. Whereas the methanolysis of the cis- and trans-dichlorides occurs with practically complete inversion, it has been confirmed that their reactions, as well as those of the dibromides, with methyl-magnesium bromide are non-stereospecific, yielding mixtures of trans- and cis-3-halo-2-methyl-tetrahydropyrans in ratios that are independent of the configurations of the starting dihalides. It has been further established that Grignard reagents cause equilibration of cis- and trans-dihalide mixtures in a reaction that is much faster than the Grignard coupling step.
|Autori:||BERTI G; CATELANI G; MONTI L; VENTRESCA G|
|Titolo:||THE STERIC COURSE OF THE REACTIONS OF 2,3-DIHALOTETRAHYDROPYRANS WITH GRIGNARD-REAGENTS|
|Anno del prodotto:||1986|
|Digital Object Identifier (DOI):||10.1016/S0040-4020(01)87552-9|
|Appare nelle tipologie:||1.1 Articolo in rivista|