Tricyclic tertiary alcohol

During the first total synthesis of taxol , R. Holton and co-workers installed an exo-methylene group on the C ring in order to set the stage for the D ring (oxetane) formation. The Burgess dehydration reaction was applied to a complex tricyclic tertiary alcohol intermediate (ABC rings) and the desired exocyclic alkene was isolated in 63% yield. 

Synthetic studies on kinamycin antibiotics in the laboratory of T. Ishikawa resulted in the elaboration of the highly oxygenated D ring with all the required stereocenters for the kinamycin skeletons.The tricyclic tertiary alcohol was converted to the corresponding xanthate and then smoothly pyrolyzed under reduced pressure to yield the desired tetrahydrofluorenone system. 

Amitriptyline Amitriptyline, 5-(3-dimethylaminopropyliden)-10,ll-dihydrodibenzocy-cloheptene (7.1.4), differs from imipramine in that the nitrogen atom in the central part of the tricyclic system is replaced by a carbon, which is bound to a side chain by a double bond. Amitriptyline (7.1.4) is synthesized by interaction of 10,ll-dihydro-A,iV-dimethyl-57f-dibenzo[a,d]cyclohepten-5-one with 3-dimethylaminopropyhnagnesium bromide and the subsequent dehydration of the resulting tertiary alcohol (7.1.3) using hydrochloric acid [ 11]. 

Fluoro- and chloro-substituted tricarbonyl chromium arene complexes can be reductively coupled with ketones, in the presence of samarium iodide, to give tertiary alcohols (Scheme 109). A related reaction of a tethered alkoxyimine furnished a tricyclic compound (Scheme 110). Samarium also promotes the formation of a benzyhc ketyl... 

Holton s plan for the synthesis of the ab ring system of taxanes e.g. 83) involves fragmentation of an easily accessible tricyclic compound derived from patchouli alcohol. Hydroxy-directed epoxidation of the tertiary alcohol (84) (from patchino 90) gives an unstable substance which undergoes gmentation in situ to provide the keto alcohol (85 Scheme 29). 

The enantioselective construction of a key tricyclic intermediate of spinosyn A utilizing a highly stereocontrolled anionic oxy-Cope rearrangement was accomplished in the laboratory of L.A. Paquette.The precursor tertiary alcohol was treated with potassium hydride in THF and the oxy-Cope rearrangement was complete within 3 hours at room temperature. Interestingly, the yield varied between 77 and 91% depending on the source of KH. 

Fig. (16). The alcohol (171) was converted to the keto ether (185) applying the standard organic reactions and this on subjection to Robinson annelation. The resulting adduct on treatment with sodium methoxide in methanol afforded the tricyclic ketone (187) which is converted to another keto ether (188). It is converted to tertiary alcohol (189) by treatment with methyllithium. Acid treatment of the alcohol produced the phenol (190). Its methyl derivative (191) is converted to pisiferol (192) by treatment with zinc and zinc iodide. Its methyl derivative (193) was converted to ester (195) via oxidation, reduction, tosylation and detosylation. The reagents mentioned accomplished its conversion to pisiferic acid (196).

The retrosynthetic disconnection of isocomene leads primarily to the intermediate tertiary carbenium ion 1, which may arise from the intermediate carbenium ion 2 by anionotropic 1,2-alkyl shift. The latter turns out to be the protonation product of the tricycle 3 containing an exocyclic CC-double bond which is generated by a WiT-TiG-methylenation of the tricyclic ketone 4. The concept behind this is formation of the cyclobutane ring in 4 by means of an intramolecular [2-l-2]-photocycloaddition of the 1,6-diene 5. The enone substructure in 5 results from hydrolysis of the enolether and dehydration of the tertiary alcohol function in (65)-l-alkoxy-2,4-dimethyl-3-(2-methyl-l-penten-5-yl)cyclohexene 6. The tertiary alcohol 6 emerges from a nucleophilic alkylation of (65)-3-alkoxy-2,6-dimethyl-2-cyclohexen-l-one 7 with metallated 5-halo-2-methyl-l-pentene obtained by GrigNARD reaction or... 

Now that we had built up the tricyclic core structure of chinensiolide B, all that was left to achieve was to install the tertiary alcohol and convert the protected secondary alcohol to a ketone. We decided to evaluate different methods to convert the trisubstituted alkene first into the tertiary alcohol and leave the deprotection and oxidation to the end. In looking at different options to... 

Renfrew et al. [597] carried out the alkylation of 2-ethoxycarbonyl-4-methoxylcyclohexanone (522) with o-methoxyphenethyl bromide (523) with subsequent decarboxylation and Grignardization, leading to the tertiary alcohol (524). Without being isolated, the latter was dehydrated and cy-clized to a mixture of isomers of the tricyclic dimethoxy derivative (525) [597]. A study of the stereochemistry of this type of cyclization has shown that in all cases the cis-A/B isomers predominate in the mixture of products [598, 599]. Selective hydrolysis of the phenolic methoxyl led to the free phenols (529) [597]. Separation of the epimeric mixture (529) gave three isomers, from which the cis-ketone (532) and the trans-ketone (533) were obtained in four stages [600, 601], Their configurations were shown by independent synthesis from the ketone (535) obtained by the scheme BC -- A [602], Chapter HI, Scheme 57. 

An ester of alanine with an arylaliphatic alcohol has shown promise as a non-tricyclic antidepressant. It may be speculated that the hindered milieu of the ester linkage protects the compound from hydrolysis by endogenous esterases. The preparation starts by reaction of pheny-lacctate 83 with methyl magnesium iodide to give tertiary carbinol 84. Acylation with 2-bromo-]>ropionyl bromide leads to ester 85 displacement of halogen with ammonia leads to alaproclate ( 6) [211. 

Atractylol, Cj5H2gO, is a sesquiterpene alcohol which forms the principal constituent of the oil of Atractylis ovata. It is a tertiary tricyclic alcohol, having the following characters —... 

The oil contains a considerable number of bi- and tricyclic primary, secondary, and tertiary sesquiterpene alcohols called vetiverols or vetivenols [261, 813-817f. These alcohols, as well as their acetates, are valuable fragrance materials. Since several varieties of vetiver grass exist and since fresh as well as air-dried roots are distilled under conditions that vary with the producer, the quality of the commercial oils differs considerably. Oil yields are up to 3%. The main producer is Indonesia (ca. lOOt/yr), followed by Haiti and Reunion. 

The O-silyl derivatives of some tertiary bicyclic or tricyclic alcohols with a cyclopropane moiety upon treatment with IOB, followed by addition of tetrabutyl-ammonium fluoride, underwent oxidation with ring expansion and formation of a,/J-unsaturated ketones, for example [22] ... 

On heating, the betaines formed from the reaction of propane sultone with tertiary amines have been found to undergo polymerisation (equation 111)167,168. Propane sultone reacts with substituted hydrazides to form sulphonic acids (equation 112)169. On the other hand, unsaturated -sultones react with hydrazides either on fusion or in a nonpolar solvent to form sultams as the major product (equation 113)169,170. In alcohols, either the corresponding sulphonic acids or hydrazine derivatives are obtained (equation 114). The unsaturated tricyclic -sultone 59 reacts with hydrazine to form the ethylpyrazole 60 (equation 115)171. Aliphatic sultones react almost quantitatively with potassium phthalimide108, and with the sodium derivative of amides (equation 116)163. 

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