Alicyclic compounds preparation

Chapters V-X deal respectively with Heterocyclic and Alicyclic Compounds Miscellaneous Reactions Organic Reagents in Inorganic and Organic Chemistry Dyestuffs, Indicators and Related Compounds Some Physiologically-Active Compounds and Synthetic Polymers. Many of these preparations are of course intended for advanced students, but a mere perusal of the experimental details of selected preparations by those whose time for experimental work is limited may assist to impress them on the memory. Attention is particularly directed to the chapter... 

Ethyl l-cyano-2-methylcyclohexanecarboxylate has been prepared by catalytically hydrogenating the Diels-Alder adduct from butadiene and ethyl 2-cyano-2-butenoate3 and by the procedure described in this preparation.4 8 This procedure illustrates a general method for the preparation of alicyclic compounds by the cyclization of <5-ethylenic carbon radicals l.6 Whereas the primary 5-hexen-l-yl radical 1... 

Only a few examples of ring syntheses by transformation of another ring have been published, as exemplified by the preparation of the sultines 168 by ring enlargement of five-membeted thiolane 1-oxides 166 (cf Section 8.10.9.2.3) and the 3,6-dihydro-l,2-dithiins 202 by catalytic transformation of vinylthiiranes 201 (cf Section 8.10.9.4.2). Because possibilities to synthesize six-membered rings with oxygen and/or sulfur as heteroatoms in 1,2-positions are rather limited, these reactions have been covered already in Section 8.10.9 together with alternative syntheses from alicyclic compounds. 

Free-radical eycUzation ( -Ethylenic compounds can be cyclized to alicyclic compounds by treatment with peroxides to generate carbon radicals. Thus ethyl l-cyano-2-methylcyclohexanecarboxylate (3) can be prepared from the tosylate of /ran.f-4-hcxene-l-ol (1) by the procedure formulated. The tosylate is condensed with... 

Tosylmethyl isocyanide (TsMIC) (120) is an easily prepared sulfone with a wide repertoire of useful reactions thus, TsMIC may be converted to ketones (121), alkanes (122) and alicyclic ketones (123) and (124), as shown in Scheme 52. The alicyclic compounds formed may be either small rings, e.g. cyclobutanone (123), or medium-sized rings like the 10-membered compound (124). In these reactions, the utility of TsMIC (120) is dependent on the good leaving group capacities of the tosyl and isonitrile moieties. The reagent (120) can also be used to synthesise heterocycles, e.g. oxazoles (125) (Scheme 53). 

Kolbe reaction The electrolytic decarboxylative dimerisation of the potassium salts of two carboxylate anions, used to prepare symmetrical R-R alicyclic compounds from RC02 K+. 

Ammonolysis of alicyclic anhydrides followed by Hofmann degradation is one of the most frequently used methods for the synthesis of alicyclic P-amino acids, since many anhydrides are commercially available cheap substances produced by Diels-Alder addition of maleic anhydride and the corresponding dienes [44], By this method, cis- and frans,-2-aminocyclohexane- and -cyclohexenecarboxylic acids, cis-2-aminocycloheptanecarboxylic acid [45], 3-ewtffo-aminobicyclo [2.2.1 ]heptane-2-ew/o-carboxylic acid, 3-e ifo-aminobicyclo[2.2.1 ]hept-5-ene-2-ertcarboxylic acid and some analogue P-amino acids have been prepared [44, 46-48], For partially unsaturated alicyclic compounds, a modified Hofmann degradation is used, sodium hypochlorite being applied to avoid bromine addition to the double bond [48,49]. 

This reaction is one of the major organic reactions for the preparation of alicyclic compounds. 

All the olefins prepared this way can be split at the double bond by hydroxylation or ozonization to furnish substituted alicyclic compounds in the case of 355 and 356 and an all-cis trisubstituted cyclopentane in the case of 358. 

Figure 7.13 Preparation of carbon-14-labeled alicyclic compounds from a,co-dif C]nitriles...

Alicyclic hydroxamic acids undergo several specific oxidative cleavage reactions which may be of diagnostic or preparative value. In the pyrrolidine series compounds of type 66 have been oxidized with sodium hypobromite or with periodates to give y-nitroso acids (113). Ozonolysis gives the corresponding y-nitro acids. The related cyclic aldonitrone.s are also oxidized by periodate to nitroso acids, presumably via the hydroxamic acids.This periodate fission was used in the complex degradation of J -nitrones derived from aconitine. 

This procedure has been patterned after the method by which the carbethoxy group is introduced into a few alicyclic ketones 6 and several cyclic ketones. Cyclohexanone has been reported to yield 50% of 2-carbethoxycyclohexanone when treated with sodium hydride and diethyl carbonate using ether as the solvent.7 The preparation of 2-carbethoxycycloheptanone using potassium f-butoxide and diethyl carbonate in benzene has been reported in 40% yield.8 Jacob and Dev report an 80% yield of the latter compound using sodium hydride as the base.9... 

---