Reaction of
2-methyl-2-phenylpropylmagnesium chloride with benzaldehyde in tetrahydrofuran gave
2,7-dimethyl-2,4,5,7-tetraphenyloctane-4,5-diol as a 1 : 2 mixture of clear
transparent crystalline plates (meso) and needles (�), 3-methyl-1,3-diphenylbutan-1-one,
benzyl alcohol, 2-methyl-2-phenylpropaneand a low yield of
3-methyl-1,3-diphenylbutan-1-ol. The distinction between the meso and the
(+)- diols was unequivocal because the unique space
group of the former requires thedimeric molecules to
lie about a crystallographic centre of symmetry. The mechanism involved in the
formation of the products of the Grignard reaction is
examined. By careful choice of reaction conditions a series of
I-aryl-3-methyl-3-phenylbutan-1-ols were prepared. Dehydration of the 1-aryl-3-methyl-3-phenylbutan-1-ols
with p-toluene sulfonic acid and a short reaction
time gives(E)-1-aryl-3-methyl-3-phenylbut-1-enes but longer reaction times
afford 3-aryl-1,1-dimethylindanes.Photolysis of the
(E)-1-aryl-3-methyl-3-phenylbut-1-enes affords
(Z)-1-aryl-3-methyl-3-phenylbut-1-enes and
trans-1-aryl-3,3-dimethyl-2-phenylcyclopropanes. Extended photolysis gives
4-aryl-2-methyl-3-phenylbut-1-enes via
trans-1-aryl-3,3-dimethyl-2-phenylcyclopropane by rupture of the cyclopropyl bond adjacent to the aryl substituent.
Reaction of selected carbohydrate aldehydes with benzylmagnesium halides: benzyl versus o-tolyl rearrangement
