New ring expansion procedure. VI. Decomposition of the magnesium salts of some 1-(.alpha.-bromobenzyl)-1-cycloalkanols and bicycloalkanols

Abstract

The results of the new ring expansion procedure applied to 2-methylcyclopentanone, 2-methylcyclohexanone, camphor, and bicyclo[2.2.2]octanone-2 are presented and discussed. Particular attention is afforded to the factors affecting product distribution. Each ketone was converted to its corresponding 2-phenyl-substituted ringenlarged ketone by the decomposition of the magnesium salt from the 1 -( -bromobenzyl)-1 -cycloalkanol.

Selective Ring Expansion Alkylation of Formyl[2.2.1]bicyclic Carbinols with C-Nucleophiles: A Unique Route to Cyclopentane Derivatives

“…However, the yields of products 15, 21, and 22 were significantly improved after the reaction time was increased (entries 6, 7, 14, 15, 17, and 18). Although the reactions with allylMgCl, n-BuMgCl, vinylMgBr, and CH 3 CCMgBr (entries,8,9,11,and 12) were individually carried out in 15 and 30 min, the yields of the corresponding products given in both time periods were almost the same. Interestingly, the reaction with phenyl ethynyl magnesium bromide (entry 13) also afforded the expected product in good yield.…”

“…However, the reaction of formyl borneol (6) with either 1 or 2.5 equiv of various Grignard reagents provided alkyl[3.2.1]bicyclic diols instead of ketones. 9 It should be emphasized that 5 underwent ring expansion only, 8 whereas 6 did consecutively undergo a ring expansion-alkylation reaction when both of them were individually treated with 1 equiv of the same reagent. These interesting results impelled us to further study the reactions of other formyl[2.2.1]bicyclic carbinol analogues with some C-nucleophiles.…”

“…In order to obtain carbinol 7 (Scheme 2), (+)-camphene (8), which is commercially available, was adopted as the starting material. Treatment of 8 with N,N-dimethyl-methanamine oxide 10 in the presence of a catalytic amount of OsO 4 (Scheme 2) provided diol 9 (91% yield, 98% de).…”

Bicyclo[2.2.2]octane-2-spirocyclohexanes, Part 5 [1] The Action of Grignard Reagents on Spirodiisophora-3′,6-dione

“…The doublets o f C-2' and C-3' were erroneously entered as singlets in that Table. Unauthenticated Download Date | 5/11/18 5:35 PM to derivatisation [21], reduction by several m e thods [10], and brom ination [11] is seen to persist in the G rignard reaction now described. In con trast, G rignard reagents interact readily with the detached bicyclo [2.2.2]octanone molecule, both saturated [9,25] and olefmic [26,27], including ex amples bearing additional substituents [25,27]. The inertness of bicyclo [2.2.2]octanone when part of the extended structure (e.g.…”

“…Cyclopentanone reacts analogously, but tends to yield additionally l-(l-hydroxycyclopentyl)cyclopentan-2-one by an intermolecular condensation [7], The steric course of the Grignard reaction in the alicyclic environment has been elu cidated by extensive studies involving steroid ke tones [8]. Recent work has shown that bicyclo- [2.2.2]octanones are also convertible into tertiary alcohols by this approach [9].…”