Lactones, preparation from

Lactones derived from 2-desoxysugars behave like normal lactones prepared from hexoses and pentoses. Rates of hydrolysis of 8-lactones are much greater than those of the Y-type. Whereas hydrolysis of... 

In the synthesis of n-altrose from D-ribose, first effected by Levene and Jacobs, the only crystalline intermediate was the characteristic calcium D-altronate -3.5 H2O. The sirupy lactone prepared from it was then reduced to n-altrose with sodium amalgam, as mentioned earlier in this review. Calcium n-altronate has been obtained from other sources also, such as the aluminum chloride rearrangement of the acetates of lactose, cellobiose and glucose and subsequent transformation of the neolactose, celtrobiose and altrose derivatives thus produced (see Section... 

Other notable reports of annulations involving nitriles were concerned with the preparation of y-lactones prepared from cyano-acetic acid derivatives and olefins in the presence of manganese(III) acetate.The "carbon-zip" ring expansion of... 

The two eudesmanolides (356) and (362) isolated from Chiloscyphus species show an intense hot taste (72). Double bond isomer (355) of (356) and (358) show weak pungency. The eudesmanolides (388—342, 344—347, 349—352) with C-6/C-7 lactone juncture and the eremophilanolides (322, 323) with C-7/C-8 lactone juncture display no pungency 66). The pungency of eudesmanolides with a lactone closed to C-8 is caused by the a-methylene-y-butyrolactone group since a-methyl-y-lactones prepared from (356) and (362) by hydrogenation are not pungent (72). 

Fleet s group applied this procedure to prepare oxetin analogues from aldono-lactones prepared from either L-rhamnose (77) [32,33] or D-xylose (82) [32, 34], affording p-amino acid precursors type 78 and 83, respectively. Triflation of the free OH followed by nucleophilic displacement led to the preparation of oxetanes with different configuration and substitution at the p-position (Scheme 4.13). The final steps involve hydrolysis of the ester and reduction of the azide to the corresponding amine, giving monomeric structures for the synthesis of small peptides. 

The regioselectivity of the addition of terminal alkynes to epoxides is improved, when the reagents prepared from the lithiated alkynes and either trifluoroborane or chlorodiethyl-aluminum arc employed (M. Yamaguchi, 1983 S. Danishefsky, 1976). (Ethoxyethynyl)lithium-trifluoroborane (1 1) is a convenient reagent for converting epoxides to y-lactones (M. Naka-tsuka, 1990 see p. 327f. cf. S. Danishefsky, 1976). 

The intramolecular oxidative earbonylation has wide synthetie applieation. The 7-lactone 247 is prepared by intramolecular oxycarbonylation of the alke-nediol 244 with a stoichiometric amount of Pd(OAc)2 under atmospheric pres-sure[223]. The intermediate 245 is formed by oxypalladation, and subsequent CO insertion gives the acylpalladium 246. The oxycarbonylation of alkenols and alkanediols can be carried out with a catalytic amount of PdCl2 and a stoichiometric amount of CuCb, and has been applied to the synthesis of frenolicin(224] and frendicin B (249) from 248[225]. The carbonylation of the 4-penten-l,3-diol 250, catalyzed by PdCl2 and CuCl2, afforded in the c -3-hydroxytetrahydrofuran-2-aeetie acid lactone 251[226J. The cyclic acetal 253 is prepared from the dienone 252 in the presence of trimethyl orthoformate as an accepter of water formed by the oxidative reaction[227]. 

The chemical properties of cycHc ketones also vary with ring size. Lower members (addition reactions, than corresponding acycHc ketones. The Cg—C 2 ketones are unreactive, reflecting the strain and high enol content of medium-sized ring systems. Lactones are prepared from cycHc ketones by the Bayer-ViUiger oxidation reaction with peracids. S-Caprolactone is manufactured from cyclohexane by this process ... 

Reaction of (T)-(-)-2-acetoxysuccinyl chloride (78), prepared from (5)-mahc acid, using the magnesiobromide salt of monomethyl malonate afforded the dioxosuberate (79) which was cyclized with magnesium carbonate to a 4 1 mixture of cyclopentenone (80) and the 5-acetoxy isomer. Catalytic hydrogenation of (80) gave (81) having the thermodynamically favored aH-trans stereochemistry. Ketone reduction and hydrolysis produced the bicycHc lactone acid (82) which was converted to the Corey aldehyde equivalent (83). A number of other approaches have been described (108). 

Perfluoro-y-butyrolactone can be prepared from 1,4 diiodoperfluorobutane by reaction with turning sulfuric acid (oleum) [7S] (equation 19) The yield depends on the concentration of sulfur trioxide One of the by-products, 4-iodoperfluo-robutyryl fluoride, can be recycled to increase the overall yield of the lactone Pure sulfur trioxide generates only perfluorotetrahydrofuran, the lodo acyl fluoride, and perfluorosuccmyl fluoride... 

The Baeyer-Villiger oxidation is a synthetically very useful reaction it is for example often used in the synthesis of natural products. The Corey lactone 11 is a key intermediate in the total synthesis of the physiologically active prostaglandins. It can be prepared from the lactone 10, which in turn is obtained from the bicyclic ketone 9 by reaction with m-chloroperbenzoic acid (MCPBA) " ... 

Curran s synthesis of ( )-A9(l2)-capnellene [( )-2] is detailed in Schemes 30 and 31. This synthesis commences with the preparation of racemic bicyclic vinyl lactone 147 from ( )-norbomenone [( )-145] by a well-known route.61 Thus, Baeyer-Villiger oxidation of (+)-145 provides unsaturated bicyclic lactone 146, a compound that can be converted to the isomeric fused bicyclic lactone 147 by acid-catalyzed rearrangement. Reaction of 147 with methylmagne-sium bromide/CuBr SMe2 in THF at -20 °C takes the desired course and affords unsaturated carboxylic acid 148 in nearly quantitative yield. Iodolactonization of 148 to 149, followed by base-induced elimination, then provides the methyl-substituted bicyclic vinyl lactone 150 as a single regioisomer in 66% overall yield from 147. 

As in 10-55 hydrazides and hydroxamic acids can be prepared from carboxylic esters, with hydrazine and hydroxylamine, respectively. Both hydrazine and hydroxylamine react more rapidly than ammonia or primary amines (the alpha effect, p. 445). Imidates, RC(=NH)OR, give amidines, RC(=NH)NH2. Lactones, when treated with ammonia or primary amines, give lactams. Lactams are also produced from y- and 5-amino esters in an internal example of this reaction. 

This is a valuable procedure because medium and large ring ethers are not easily made, while the corresponding thiono lactones can be prepared from the readily available lactones (see, e.g., 10-23) by Reaction 16-10. 

When heated in ethylene chloride at 80 °C for 3h the y9-ketosulfide 1203 reacts with the trimethylsilyl ester of polyphosphoric acid (PPSE) 195 (prepared from P2O5 and HMDSO 7) to give 36% 1204 and 8% 1205, whereas the lactone 1206 affords with PPSE 195 the unsaturated sulfide 1207 in 93% yield [27] (Scheme 8.10). 

Deoxy-5-fluoro-D-glucose and -L-idose were synthesized from 1,2-(9-isopropylidene-a-D-glucofuranurono-6,3-lactone (285). Treatment of l,2-0-isopropylidene-5-0-triflyl-a-D-gluco- (286 prepared from 285) and -) -L-ido-furanurono-6,3-lactones (289 prepared from 288), with BU4NF... 

Fom- title compounds, 5-deoxy KDG Me estw, 5-epi KDG Me ester, 4-0-Me KDG Me ester and 4-deoxy KDG Me ester were prepared either from D-glucono-l,5-lactone or from 1,2 5,6 di-O-isopropylidene-D-mannitol. Biological tests perfcHined rat these molecules have shown that the compounds modified on the C-5 position (5-deoxy KDG Me ester and 5-epi KDG Me ester) are gratuitous inducers of the e>q>ression of pectinase genes in the phytopathogenic bacteria Erwinia Chrysanthemi when the C-4 modified molecules (4-0-Me KDG Me ester and 4-deoxy KDG Me ester) are not inducers. 

Lactones can be protected as dithiolane derivatives using a method that is analogous to ketone protection. The required reagent is readily prepared from trimethyl-aluminum and ethanedithiol. 

The addition of Grignard reagents to aldehydes, ketones, and esters is the basis for the synthesis of a wide variety of alcohols, and several examples are given in Scheme 7.3. Primary alcohols can be made from formaldehyde (Entry 1) or, with addition of two carbons, from ethylene oxide (Entry 2). Secondary alcohols are obtained from aldehydes (Entries 3 to 6) or formate esters (Entry 7). Tertiary alcohols can be made from esters (Entries 8 and 9) or ketones (Entry 10). Lactones give diols (Entry 11). Aldehydes can be prepared from trialkyl orthoformate esters (Entries 12 and 13). Ketones can be made from nitriles (Entries 14 and 15), pyridine-2-thiol esters (Entry 16), N-methoxy-A-methyl carboxamides (Entries 17 and 18), or anhydrides (Entry 19). Carboxylic acids are available by reaction with C02 (Entries 20 to 22). Amines can be prepared from imines (Entry 23). Two-step procedures that involve formation and dehydration of alcohols provide routes to certain alkenes (Entries 24 and 25). 

There have been several syntheses of P-D lactone that were based on carbohydrate-derived starting materials. The starting material used in Scheme 13.42 was prepared from a carbohydrate produced in earlier work.27 The relative stereochemistry at C(4)... 

The stereochemistry of the enol lactones was established by correlation with the structure of derivative 121, prepared from bicuculline (88), whose configuration as Z was determined by X-ray analysis (95). In this correlation... 

A series of N-substituted narceine amides (Section III,D,1) was prepared from 101 under the action of primary amines (100). Acid-catalyzed dehydration transformed these amides to corresponding imides (ene lactams) of the ( )-narceine imide (117) type (100). Similar transformations were performed in the hydrastine series (101). JV-Methylhydrastine (98) when treated with dilute ammonium hydroxide gave hydroxy lactam 127, which was dehydrated to (Z)-fumaridine (113) (5). Sodium borohydride was able to reduce the stilbene double bond in 98 to produce saturated lactone 132 (5). 

Steric hindrances may also be the reason why quaternary salts of 8-alkylnarcotoline (130) were transformed during Hofmann degradation to analogous keto acids (131) (111,112) and not to the enol lactones (Scheme 24). In some cases (5,87) the keto acids and their esters have been synthesized from the corresponding enol lactones by hydration (Section III,A,2). Nornarceine (107) was prepared from JV-benzyl-(—)-a-narcotinium bromide (139, X = Br) by Hofmann degradation followed by N-debenzylation and ester hydrolysis (109). 

---