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Tricyclic alcohol

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 —... [Pg.160]

Mioskowski et al. have demonstrated a route to spirocyclopropanes. As an example, treatment of epoxide 100 with n-BuLi in pentane stereoselectively gave tricyclic alcohol 101, albeit in only 47% yield (Scheme 5.21) [29]. With a related substrate, epoxide 102 stereoselectively gave dicydopropane 103 on treatment with PhLi uniquely, the product was isolable after column chromatography in 74% yield [35]. As was also seen with attempts to perform C-H insertion reactions in a non-transannular sense, one should note that steps were taken to minimize the formation of olefin products, either by the use of a base with low nudeophilicity (LTM P) and/or by slow addition of the base to a dilute solution (10-3 m in the case of 102) of the epoxide. [Pg.156]

Solvolysis of the endo bicyclic compound (24) (X=ONs, p. 446, or Br) gave mostly the bicyclic allylic alcohol (27), along with a smaller amount of the tricyclic alcohol (31), while solvolysis of the exo isomers (28) gave mostly (31), with smaller amounts of 27 Thus the two isomers gave entirely different ratios of products,... [Pg.1386]

Conversion of Xa to the Hydrlndan XIII. The ultimate synthetic target of these investigations is a mixture of the tricyclic alcohols XIV (Scheme II). In the Sih synthesis (3) the methyl ester... [Pg.431]

As exemplified by Thompson for the case of tricyclic alcohol 1 [Eq. (1)], alkox-ide has a strong coordinative ability to the metal, and high diastereoselectivity is realized in spite of the presence of a proximal bulky substituent in dihydrofuran derivatives [Eqs. (3) and (4)] [17]. [Pg.650]

Teruya, T., Nakagawa, S., Koyama, T., Suenaga, K., and Uemura, D. (2002). Terpiodiene A novel tricyclic alcohol from the Okinawan sponge Terpios hoshinota. Chem. Lett. 31,... [Pg.184]

A simitar situation appears to exist ii> the attempted opoxidation t the unsaturated tricyclic alcohol depicted in Eq. (56). [Pg.355]

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] ... [Pg.86]

Isopropyl anisole (171) was converted to bromide (172) by metalation, formylation and bromination. Alkylation with cyclopropyl ketoester produced (173) whose transformation to alcohol (174) was achieved by saponification, decarboxylation and reduction.. Its conversion to homoallylic bromide (175) was accomplished by the method of Julia et al. [56]. Alkylation of ethyl acetoacetate with bromide (175) furnished p-ketoester (176). It was subjected to cyclization with stannic chloride in dichloromethane. The resulting tricyclic alcohol provided the olefinic ester (177) by treatment with mesylchloride and triethylamine. Epoxidation followed by elimination led to the previously reported intermediate (146) whose conversion to triptolide (149) has already been described. [Pg.207]

Fig (20) Bromide (172), prepared from alcohol (171) on alkylation yields (173) which is converted to (174) without any difficulty. Conversion of (174) to homoallylic bromide (175) is accomplished by the method of Julia. On alkylation followed by cyclization generated the tricyclic alcohol which undergoes dehydration to yield unsaturated ester (177) which is converted to unsaturated lactone (146) by epoxidation and elimination. [Pg.208]

In another attempt to mimic the in vivo cyclization of humulene, Mlotkiewicz et have shown that treatment of humulene 4,5-epoxide (272) with boron trifluoride etherate leads to the formation of the two tricyclic alcohols (273) and (274) in 70% yield. The carbon skeleton of these two compounds is exactly that found in africanol (276) and the more recently isolated keto-angelate (275). Further elaboration of the alcohol (273) has in fact resulted in a biomimetic synthesis of the keto-alcohol corresponding to (275). This work constitutes the first example of the direct conversion of a humulene derivative into a naturally occurring compound. [Pg.42]

In an examination of the mechanism of the solvolysis of the tricyclic alcohol (627) which led to the successful synthesis of seychellene (628), Frater has shown that the minor product is the tricyclic olefin (629) which is formed by the process depicted in Scheme 79. An alternative synthesis of seychellene (628) and patchouli alcohol (635) depends upon the construction of the key tricyclic ketol (631) by an intramolecular Michael reaction followed by an aldol cyclization of (630) (Scheme 80). The minor ketol (632) can be converted into epi-sey-... [Pg.96]

During a total synthesis of the diterpenoid enmein, the tricyclic alcohols (47) and (48) were converted into a range of c-ring ketones (Scheme 5). The degree of reduction and the ease with which it occurs, relative to (23), make it apparent that intramolecular protonation is involved here also. ... [Pg.496]

The tricyclic alcohol (130) is an intermediate in the synthesis of rimuene. Hydroboronation of its tetrahydropyranyl ether and then oxidation with iodine and lead tetra-acetate afforded the 6—18 ether which could be cleaved and oxidized to a keto-acid. Such derivatives might form suitable intermediates for the synthesis of the rosane lactones. O-MethyI-14-methyl podocarpic acid has been synthesized "" by a conventional ring a + ring c route. [Pg.153]

Diels-Alder adduct (2) of allyl alcohol with cyclopentadiene. The unsaturated alcohol was converted into 6-chloromethyl-3-oxatricyclo 3.2.I.O loctane (3). For cyclization of (3) to the tricyclic alcohol (4), lithium in tetruhydrofurane proved superior to sodium in toluene. The alcohol (4) has a compurutively strained cycio-butune ring, but was converted easiiy into the parent hydrocarbon by oxidation (CrOfl-Py) and Wolff-Kiihner reduction. [Pg.289]

Even the cyclopropane-diazonium ions (4<59)366 367 and (474)368 decompose with participation by the double bond. The hydrolysis of bicyclo [4.3.1] dec-6-en-l-yl p-nitrobenzoate (475) is accelerated by a factor of 120 and affords, inter alia, the tricyclic alcohols (47<5)369. A related case of transannular participation, leading to ion pair return, was observed with 5-cyclodecen-l-yl p-nitrobenzoate (7 >4)112 (Section 4.2.3). [Pg.232]

We discovered the thermal reversibility of the diene cyclometallation when we attempted cyclization of the diene 9 (Scheme 3) (8,9). The reaction proceeded to completion after two hours at room temperature, but rather than the expected tricyclic alcohol 13, the product was the dimer 11, from the reaction of two monosubstituted alkenes. We repeated the cyclozirconation, but let it proceed for a longer time. After 18 hours at room temperature, a new product had appeared (TLC analysis). After 1.5 hours at 75°C, the reaction was complete. The tricyclic alcohol 13 was isolated in 63% yield from 9. [Pg.207]

Formula 175 represents the incorrect planar structure proposed by Brindley and Pyman 147) in 1927 for emetine (1). In this connection, Harada et al. 148) synthesized the four stereoisomers possible for ( )-C-noremetine Pyman [( )-176] and isolated them in the form of hydrobromide salts. Takacs and Boito 149) synthesized the (-)-tricyclic alcohol 177, a one-carbon homolog of the Alangium alkaloid (-)-protoemetinol (34), from the chiral formamidine 117 in 36% overall yield via a five-step route proceeding through the stereoselective iron-catalyzed cyclization of the key intermediate 178. [Pg.298]

Shortly after these communications, the alcohol (127), named a-acorenol, was found to occur naturally in the wood of Juniperus rigida and Tomita and Hirose also demonstrated its facile cyclisation with formic acid to ( — )-(z-cedrene (123) in greater than 90% yield. The corresponding diene (132), a-acoradiene, which was also converted to (—)-a-cedrene, was found in the same source. Subsequently, Hirose et al. isolated four other related sesquiterpenes from the same species. These are j5-acoradiene (133), y-acoradiene (134), -acoradiene (135), and )3-acorenol (136). The above authors also reported a tricyclic alcohol... [Pg.73]

Homoallylic alcohols are also suitable for controlling the introduction of an alkyl chain, as shown by the synthesis of the diterpenoid atractyligenin61, The starting tricyclic alcohol is converted to the selenocarbonate, a suitable radical precursor. Treatment with tributyltin hydride initiates the stereoselective cyclization which affords the bridged lactone system, an intermediate in the diterpenoid synthesis. Due to the low cyclization rate, tributyltin hydride is added slowly to suppress the formation of noncyclized reduction products. [Pg.72]

Other impressive results have been reported, for example, mfo-5-acylnorbornene 14 undergoes intramolecular cycloadditions to give polycyclic oxetanes 1562-65. Interestingly, the quantum yield of cyclization is favored by increasing bulk of the substituent. Reductive cleavage by lithium aluminum hydride occurs selectively to allow the synthesis of tricyclic alcohols 16. [Pg.943]

Asymmetric Michael reactions have heen conducted with assistance of C2-symmetric malonamides derived from (5)-ptohne esters/ 2-Methyl-3,4,5,6-tetrahydropyridine and 2-cyclopentenone are condensed to afford a tricyclic alcohol. The reaction starts from Michael reaction of the endocychc enamine isomer and as the double bond shifts to the exo-cychc position an intramolecular aldol reaction follows. If the imine is hthiated, the initial Michael reaction (CuBr-catalyzed) then involves the exocyclic carbon. ... [Pg.372]

If a carbonyl group is attached a to position 1 of the pericyclic system, the oxy-Cope rearrangement of divinylcyclohexanes results in the formation of medium ring enolates, which after proton transfer undergo a transannular vinylogeous aldol-type reaction (probably a transannu-lar, intramolecular Michael-type reaction). For example, tricyclic alcohol 4 is obtained via such a reaction sequence from 1 in 45% yield1129. [Pg.396]

The structure of berkheyaradulene (630), isolated from the roots of Berkheya radula, has been deduced from spectroscopic evidence and transformation into a tricyclic alcohol (631) whose structure was established by X-ray analysis. ... [Pg.158]


See other pages where Tricyclic alcohol is mentioned: [Pg.54]    [Pg.527]    [Pg.40]    [Pg.512]    [Pg.116]    [Pg.72]    [Pg.485]    [Pg.44]    [Pg.740]    [Pg.248]    [Pg.40]    [Pg.85]    [Pg.86]    [Pg.32]    [Pg.814]    [Pg.512]    [Pg.63]    [Pg.105]    [Pg.117]    [Pg.606]    [Pg.1549]    [Pg.814]    [Pg.479]   
See also in sourсe #XX -- [ Pg.40 ]

See also in sourсe #XX -- [ Pg.545 ]




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