- SYNTHESIS OF 1,3-DIOL DERIVATIVES FROM STERICALLY OVERCROWDED OXIRANES. RING-OPENING REACTIONS OF 1-t-BUTYL-1,2-EPOXYCYCLOHEXANE.
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The acid-catalysed ring-opening reactions of 1-t-butyl-1,2-epoxycyclohexane (1) (methanolysis, hydrolysis, and trichloroacetolysis in non-protic solvents) lead to very complex mixtures.In these reactions, in addition to the non-addition products in which the t-butyl skeleton is still present, considerable amounts of other products are formed.These compounds include 1,3-secondary addition products and other rearranged non-addition products which arise by rearrangement of the original skeleton of (1), by methyl group migration; the aldehyde (20) which is lackig both the t-butyl group and the cyclohexane skeleton is also obtained.However the opening reactions of (1) in acid media are highly regioselective, most of the reaction products arising from C-O breaking on the tertiary carbon.The structures and the configurations of all the reaction products have been well established by a study of their i.r. and n.m.r. data; however, in some cases the structures and configurations were confirmed either through unequivocal syntheses and/or chemical correlations.The stereoselectivity of the trichloroacetolysis reactions of (1) is not completely anti, even if the amounts of 1,2 adducts formed are somewhat small, and the syn/anti ratio increases with the polarity of the solvent.The results obtained were rationalized through a mechanism analogous to that previously proposed for 2-aryl- and 2-ethynyl-oxiranes in which different kinds of carbenium ion species are involved.
- Corona, Tiberio,Crotti, Paolo,Ferretti, Maria,Macchia, Franco
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p. 1607 - 1616
(2007/10/02)
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- KINETIC CONTROL IN THE BENZYLIDENATION OF SOME 1-ALKYLCYCLOHEXANE-CIS-1,2-DIOLS
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Acid-catalysed benzylidenation reactions of a series of alkyl substituted derivatives of cyclohexane-cis-1,2-diol have been studied.Preferential formation of the exo-phenyl benzylidene acetal was observed in the initial kinetic phase of the reaction of th
- Baggett, Neil,Mosihuzzaman, Mohammed,Webber, John M.
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p. 347 - 356
(2007/10/02)
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