Di-y-lactones

Of particular interest is die example of diethyl 2,5-diiodoadipate [13], which was added to two equivalents of methyl 10-undecenoate [2b] to form the di-y-lactone [14] of a tetracarboxylic acid containing 26 C-atoms in the molecule chain in a yield... 

The fungal metabolites avenaciolide (86), isoavenaciolide (87 a) (cf. ethisolide, 87 b), and canadensolide (88) (Scheme 22) form an interesting trio of structurally related di-y-lactones. Avenaciolide was the forerunner... 

Y-Halo-esters undergo lactonization in the presence of a silica gel catalyst. 3-(l,l-Dihydroxypropyl)glutaric acid di-y-lactone has been used in a short synthesis of methylenomycin. ... 

On treatment with trimethyl(2-propenyl)silane and titanium(IV) chloride, chiral methyl fi-formylcarboxylates give di- and tetra-substituted y-lactones with moderate to good stereoselectivity. Participation of seven-membered ring chelates was suggested65. 

A simple application of the reaction may be mentioned. Refluxing of (I) with 48 per cent, hydrobromic acid and glacial acetic acid leads to hydrolysis and decarboxylation and the production of a mixture of the y-lactone yy-di-phenylbutyrolactone (II) and the isomeric unsaturated acid yy-dlphenyl-vinylacetic acid (III) reduction by the Clemmensen method or catalytically... 

Enantiomeric distribution of -y-lactone homologues from different apricot cultivars. Identification of dihydro-actinidiolide (co-eluted with y-Cl 1 on DB-1701) Fused silica retention gap (10 m X 0.25 mmi.d.) coupled to a DB-1701 column (15 m X 0.25 mm i.d. 1 pun 1 pjnfilm thickness) Glass capillary column (38 m X 0.2 mm i.d.) coated with heptakis (3-0-acetyl-2,6-di-0-pcnlyl)-/3-cyclodextrin 3... 

Levopimaric acid forms an epidioxide (63) which thermally rearranges to a di oxide (65). On photolysis the epidioxide gives both the diepoxide and the 12-keto-epoxide (64). Treatment of the epidioxide with triphenylphosphine affords a monoepoxide which was shown to be the 8a(14a)-epoxide (66). On further epoxidation this gave the diepoxide, levopimaric acid dioxide. The photochemistry of ring c diterpenoid y-hydroxydienones has also been investi-gated. " Thus compound (67 R = H or Et) afforded firstly the spiro-diketone (68) and then the unsaturated y-lactone (69). 

The C1-C13 segment 206 of halichondrin B (205) has been recently synthesized with improvements from 210 and 211. The Cl-Cl 1 segment 210 was prepared from L-mannonic-y-lactone (212) (O Scheme 24). Di-O-cyclohexylidene protection of 212 followed by DIBALH reduction and Wittig reaction gave 213. Stereoselective dihydroxylation and acetylation of 213 provided 214. C-Glycosidation of 214 with methyl 3-trimethylsilylpent-4-enoate and BF3 Et20 afforded a-glycoside 215 exclusively. This compound was transformed into 206 via the 7-step manipulation as shown in O Scheme 24. 

Diethoxyphosphinyi-2-buten-4-oli reacts with lithiated dithianes followed by an intermolecular Wittig-Homer reaction to produce fused y-lactones (equation 37). The reaction of 2-lithio-l,3-di-thianes with nitroarenes gives 2- or 4-[(l,3-dithian)-2 -yl]cyclohexa-3,5(or 2,5-)-diene-l-nitronate compounds (conjugate addition products), free nitroarene r cal anions (redox products), 1,3-dithianes and 2,2 -bis( 1,3-dithianes). ... 

Lactone formation, by intramolecular condensation of a-acetoxy-ketones in strongly basic media, has been examined systematically. Lithium di-isopropylamide in ether is effective as the base conditions must be chosen according to the reactant. Scheme 8 illustrates successful reactions, which afforded either the /3-hydroxy-y-lactone or the butenolide, depending upon the ease of adoption of the conformation necessary for elimination of water. The method appears to be limited to tertiary a-acetoxy-ketones. 

LACTONES Bis(3-dimethylaminopro-pyl)phenylphosphine. Copper(I) tri-fluoromethanesulfonate. Di-n-butyltin oxide. Dichlorobisf triphenyl-phosphine)-palladium. Ruthenium tetroxide. a-LACTONES Iodosobenzene. y-LACTONES Trimcthylsilylacetonitrile. 

Di-i-butylaluminum hydride, Al(i-Bu)jH. For the reduction of a, 3-unsaturated y-lactones to furanes, the reagent is used interchangeably with triisobutylaluminum, which see. 

Reduction of unsaturated lactones, Minato and Nagasaki found that a,jS-un-saturated y-lactones are reduced by either tri-i-butylaluminum or di-/-butylaluminum hydride in tetrahydrofurane to give the corresponding furane derivative, for example... 

Furthermore, enantio-MDGC, employing heart-cutting techniques from DB-1701 as the preseparation column on to heptakis (3-0-acetyl-2,6-di-0-pentyl)-P-cyclodextrin as the chiral main column, was described by Mosandl et al. /2S7 as a powerful tool in the direct enantiomer separation of chiral y-lactones from complex matrices without any further clean-up or derivatization procedures. 

Di-0-acetyl-3-deoxy-D-arabino-1,4-lactone D-threo-Pentoic acid, 3-deoxy-y-lactone, 2,5-diacetate (10) (79580-65-7)... 

In connection with a synthesis of the hydroazulenic sesquiterpene kessanol (304), Knoevenagel condensation of photocitral-A (302) with ethyl cyanoacetate was found to give (303) as a single isomer. The following sequence includes an intramolecular Prins reaction initiated with SnCU. In Isobe s synthesis of vemolepin (307) the two carbons of the -y-iactone are introduced by a Knoevenagei condensation. Reaction of ketone (305) with di-f-butyl maionate followed by treatment with DBU affords (306), which is transformed to the a,a -dihydroxy compound (308). Hydrolysis of the esters foliowed by decarboxy-iation, formation of the y-lactone, Mannich reaction and elimination yields vemolepin (307 Scheme 58).3"... 

The y-lactones described below can be prepared in good yield in a one-step process by radical addition of primary fatty alcohols to acrylic acid, using di-terf-butyl peroxide as a catalyst. A patent claims a high yield when the reaction is carried out in the presence of alkali phosphates or alkali sulfates [196]. 

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