P.y-Epoxy alcohols

P,Y-Epoxy alcohols. Treatment molecular sieves results in the format atom comes from the OOH group the ing from an allylic alcohol, an epoxy centers can be prepared through phot transfer. 

Intramolecular oxonium ylide formation is assumed to initialize the copper-catalyzed transformation of a, (3-epoxy diazomethyl ketones 341 to olefins 342 in the presence of an alcohol 333 . The reaction may be described as an intramolecular oxygen transfer from the epoxide ring to the carbenoid carbon atom, yielding a p,y-unsaturated a-ketoaldehyde which is then acetalized. A detailed reaction mechanism has been proposed. In some cases, the oxonium-ylide pathway gives rise to additional products when the reaction is catalyzed by copper powder. If, on the other hand, diazoketones of type 341 are heated in the presence of olefins (e.g. styrene, cyclohexene, cyclopen-tene, but not isopropenyl acetate or 2,3-dimethyl-2-butene) and palladium(II) acetate, intermolecular cyclopropanation rather than oxonium ylide derived chemistry takes place 334 ). 

Zinc borohydride was effective for the reduction of a,P-epoxy ketones (49) to the corresponding anti-a,3-epoxy alcohols (50) in ether at 0 °C irrespective of the substituents on the epoxide (equation 14). The selectivity was rationalized by intramolecular hydride delivery from a five-membered zinc chelate avoiding the epoxide ring. In a limited study of the stereoselective reduction of y,8-epoxy ketones (51), LAH and di-2-(o-toluidinomethyl)pyrrolidine in ether at -78 C gave the desired c/j-epoxy alcohols (52) required for ionophore synthesis with good selectivity (>10 1) (equation 15). ... 

A novel regioselectivity is observed with trans-2,3-epoxy alcohols. The C-1 attack of 1,2-epoxy alcohol formed by the Payne rearrangement proceeds predominantly, and a/iri-P, y-dihydroxyalkynes are obtained stereospecificdly (equation 37).The reaction is employed in the synthesis of a pheromone, eO f o-6-acetoxyhexadecan-5-olide. 

Kalsi P S, Gupta B C, Chahal S, Mehta Y K, Wadia M S 1979 Structure of isokhusinoloxide. A new sesquiterpene epoxy alcohol from vetiver oil. Bull Soc Chim Fr Part 2, 599-600... 

The full paper on the synthesis of onikulactone and mitsugashiwalactone (Vol. 7, p. 24) has been published.Whitesell reports two further useful sequences (cf. Vol. 7, p. 26) from accessible bicyclo[3,3,0]octanes which may lead to iridoids (123 X=H2, Y = H) may be converted into (124) via (123 X = H2, Y = C02Me), the product of ester enolate Claisen rearrangement of the derived allylic alcohol and oxidative decarboxylation/ whereas (123 X = 0, Y = H) readily leads to (125), a known derivative of antirride (126) via an alkylation-dehydration-epoxi-dation-rearrangement sequence. Aucubigenin (121 X = OH, R = H), which is stable at —20°C and readily obtained by enzymic hydrolysis of aucubin (121 X = OH, R = j8-Glu), is converted by mild acid into (127) ° with no dialdehyde detected sodium borohydride reduction of aucubigenin yields the non-naturally occurring isoeucommiol (128 X=H,OH) probably via the aldehyde (128 X = O). ... 

About 20 oxygenated sesquiterpenes have been identified from pepper oil. They are 5,10(15)-cadinen-4-ol,caryophylla-3(12), 7(15)-dien-4-P-ol, caryophylla-2,7(15)-dien-4- 3-ol, caryophylla-2,7(15)-dien-4-ol, P-caryophellene alcohol, caryophyllene ketone, caryophellene oxide, epoxy-dihydrocaryophellene, cis-nero-lidol, 4,10,10-trimethyl-7-methylene bicycle-(6.2.0) decane-4-carboxaldehyde, cubenol, epi-cubenol, viridiflorol, a- and P-bisabolols, cubebol, elemol and y-eudesmol. 

A soln. of 85%-m-chloroperoxybenzoic acid in methylene diloride added to a stirred ice-cooled soln. of 5-norbornen-2-ol in the same solvent, after 2 hrs. treated with a soln. of 2,2,6,6-tetramethylpiperidine hydrochloride in methylene chloride followed by additional m-chloroperoxybenzoic acid soln., and the product isolated after 1.5 hrs. exo-5,6-epoxy-2-norbornanone. Y 86%. J. A. Celia, J. A. Celia, J. A. Kelley, and E. F. Kenehan, J. Org. Chem. 40, 1860 (1975) oxidation of alcohols with N-oxide radicals cf. B. Ganem, ibid. 40, 1998 ketones from sec. alcohols with m-chloroperoxybenzoic acid/HCl cf. J. A. Celia, J. P. McGrath, and S. L. Regen, Tetrah. Let. 1975, 4115 review of N-oxide radicals s. H. G. Aurich and W. Weiss, Topics Curr. Chem. 59, 65 (1975). 

Other examples were also described by Schobert et al ot,P-Unsaturated esters can be prepared in a one-pot process from a variety of alcohols. In the first step, the alcohols are oxidized selectively by PhI(OAc)2/2,2,6,6-tetramethyl-l-piperidinyloxy (TEMPO) to aldehydes that are then subjected to Wittig olefination with ethox-ycarbonylmethylene- or a P-oxomethylenephosphorane (Scheme 94). Substituent Y may include unsaturated, hydroxyalkyl and aryl groups, as well as epoxy-, sugar and pinane-based substituents. 

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