Synthesis of lactones

Scheme 25. Construction of the ABCDEFG ring system (87) synthesis of lactone 100.

An analogous dehydration in the synthesis of lactone substituted derivatives of digitoxigenin is reported in reference [21a]. 

Another recent example of sonochemical substitution is in the preparation of 7r-allyllactone(tricarbonyl)iron complexes, which are useful synthetic intermediates in the synthesis of lactones and lactams (185). Upon... 

A 1992 patent describes the carbonylation of EO to yield /3-propiolactone using a mixture of Co2(CO)8 and 3-hydroxypyridine.982 A recent re-investigation of this system has indicated that the major product is the alternating copolymer, a polyester, catalyzed by the [Co(CO)4] anion (Scheme 24).983 The synthesis of lactones via this methodology has successfully been achieved using Lewis acidic counter-cations (Scheme 25) 984,985 a similar strategy allows /3-lactams to be... 

Palladium-catalyzed cyclic carboxylation of dienes can be utilized for the synthesis of lactones.2 Polymer-supported Pd catalyst could also be used for this reaction (Scheme 42).61 The reaction is initiated by dimerization of two molecules of diene to give a bis-7r-allylpalladium intermediate such as 123. The incorporation of C02 takes place at the internal position of an allyl unit to afford the 7r-allylpalladium carboxylate 124 which, after reductive elimination/ cyclization, yields the (5-lactone 121 (Scheme 43). 

Diastereoselective synthesis of lactones.1 Acylation of the enolate (LDA) of the vinylogous urethane (1) results in a product (2) that on reduction with LiBH[CH(CH3)C2H5]3 (3) forms the anft-lactone (4) exclusively (equation I). This two-step synthesis of lactones is the equilvalent of an aldol condensation between... 

This approach is applicable to cross-coupling reactions of allenoic acids and acrolein, which lead to the synthesis of lactones (Scheme 16.98) [104]. The reaction proceeds via oxypalladation of an allenoic acid to give rise to a vinylpalladium species. 

The chemistry of a-haloketones, a-haloaldehydes and a-haloimines Nitrones, nitronates and nitroxides Crown ethers and analogs Cyclopropane derived reactive intermediates Synthesis of carboxylic acids, esters and their derivatives The silicon-heteroatom bond Synthesis of lactones and lactams Syntheses of sulphones, sulphoxides and cyclic sulphides Patai s 1992 guide to the chemistry of functional groups—Saul Patai... 

Synthesis of Lactone Ring Substituted Analogues of AHLs. 300... 

The environmentally benign synthesis of lactones has attracted attention because of their importance in natural product chemistry. The oxidative cyclization of diols via carbon-oxygen bond formation is the most well-known approach for the synthesis of lactones [70]. 

Two different classes of optically active a-hydroxylated lignans have been prepared from sugars by Yamauchi and co-workers lactone lignans [47, 48] and tetrahydrofuran lignans [49, 50]. In both cases, only model compounds were synthesized, such as lactone lignan 55 (Scheme 13), as a result of the synthetic strategy. The key intermediate for the synthesis of lactone lignan... 

Since the alkene formed in this reaction can further react with other alkenes, many products should be formed in the cross-metathesis (CM). Therefore, in the early days, only ring-closing metathesis (RCM) of diene was investigated. It is known that the reaction is catalyzed by a transition metal. Pioneering work on olefin metathesis was undertaken by Villemin and Tsuji, who reported the synthesis of lactones using alkene metathesis ... 

An alternative synthesis of lactone derivatives (178) from (D)-( + )-mannitol was also reported, c.f. ... 

Scheme 2.2.7.8 Synthesis of lactone (R) -16, a natural fragrance compound occurring in the essential oil of labdanum resin [30].

The biotechnological synthesis of lactones has reached a high standard. Besides microbial production, lactones can also be enzymatically produced. For instance, a lipase-catalysed intramolecular transesterification of 4-hydroxy-carboxylic esters leads enantioselectively (ee>80%) to (S)-y-lactones the chain length may vary from C5 to Cl 1 [13]. y-Butyrolactone can be produced in that way with lipase from Mucor miehei [30]. 

Research Focus Synthesis of lactone containing positive resist copolymer compositions having improved line edge roughness resolution. 

Scheme 4.1 Synthesis of lactone-terminated polybutadiene (LTPB).

Ionic ring-opening reactions of cyclopropanes under solvolytic conditions followed by ring-closure of the primarily produced cations have been employed for the synthesis of lactones, tetrahydrofuranes, and pyranes, respectively, as shown below [176]. 

For a review of the synthesis of lactones and lactams, see Wolfe Ogliaruso, in Palai The Chemistry of Acid Derivatives, pt. 2 Wiley New York, 1979, pp. 1062-1330. For a list of methods for converting hydroxy acids to lactones, with references, see Ref. 508, pp. 941-943. 

Medium-sized lactones A new method for synthesis of lactones that is particularly useful in the case of medium sized ones involves the hypoiodite reaction with a catacondensed lactol such as 1, which results in cleavage to the ten-membered isomeric iodo lactone 2. Phoracantholide I (3) is obtained on reductive removal of iodine. 

M. A Ogliaruso and J. E Wolfe, Synthesis of Lactones and Lactams. Updates to the Chemistry of Functional Groups, J, Wiley Sons, New York (1993)... 

If the halide and the hydroxy group are present in the same molecule, reaction (107) leads to the synthesis of lactones.484 With complex (102) as catalyst a series of butenolides were prepared in good yields from vinyl iodides (equation 110). Four- and six-membered ring lactones and a-methylene lactones were prepared. 5,486 The mechanism proposed was analogous to that of Scheme 37. This cyclization has been used in the synthesis of the natural product zearalenone.487 PdCl2 was the catalyst. 

Oligaruso MA, Wolfe JF (1993) In Patai S, Rappoport Z (eds) Synthesis of lactones and lactams. Wiley, Chichester, pp 162-168... 

A brief review of procedures for asymmetric metal-catalyzed Baeyer-Villiger oxidations is given with asymmetric copper-catalyzed synthesis of 3-phenyl-2-oxepanone as representative of the enantioselective synthesis of lactones from cyclic ketones . 

The enzymatic Baeyer-Villiger oxidation enantioselective synthesis of lactones from mesomeric cyclohexanones, J. Am. Chem. Soc. 1988, 110, 6892-6893. 

M. Fetizon, M. Golfier, and J. M. Louis, Highly selective oxidations of diols by silver carbonate, Chem. Commun., (1969) 1102 A new synthesis of lactones application to ( )-mevalonolactone, ibid., (1969) 1118-1119. 

Reactions have been described for RH = amines, alcohols, aromatics, aliphatics, perfluoroalkyls, hydrogen halides, and thiols (167). Another recent use of S2OfiF2 in organic chemistry has been in the synthesis of lactones by the remote oxidation of carboxylic acids using a... 

This is a key stage in the synthesis of lactonic Lythraceae alkaloids published by Hanaoka et al., Loev et al., and Wrobel and Gol biewski. This reaction was studied by several groups of chemists (64, 66-69). It proceeds in good yield for a variety of aromatic aldehydes usually in dilute aqueous or alcoholic solutions of sodium hydroxide to yield 2-quinolizidones. Two diastereomers, 138 and 139, defined by the relative stereochemistry at C-4 and C-10 are formed in the condensation In the trans-quinolizidone (139) the C-4 and C-10 hydrogens are trans to one another. In the cw-quinolizidone (138) they are cis. 

Various methods have been explored for the synthesis of lactones by cycloaddition reactions. The most common of these types of reaction is the [2+2] cycloaddition of aldehydes and ketene. Palladium(ll) complexes, [Pd(dppb)2(PhCN)2](BF4)2, have been shown to be efficient catalysts for this reaction (Equation 34) <2000CC73>. 

Scheme 4.7. Synthesis of lactones and cyclic ethers from halocyclopropanes.

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