Integerrinecic acid lactone

The (— )-senecic acid was also obtained by Mattocks and Warren (161) from the hydrolysis of isosenecionine obtained from retrosine by oxidation with sodium metaperiodate and reaction of the resulting keto compound with methylmagnesium iodide. The (-)-senecic acid was converted to (—)-integerrinecic acid lactone. The oxidation of this (— )-senecic acid with lead tetraacetate gave a keto acid (2,4-DNP, mp 183°, [aJu —11.6°) enantiomeric with that from (- -)-senecic acid (see Chart III). 

Two six-membered necic acid lactones 46 (integerrinedc acid lactone) and 47 (senedc acid lactone) having an exo-a-methylene moiety were synthesized by Wiemer et al. [45] in the stereocontrolled Horner-Wittig condensation of the a-phosphonolactone 48 with acetaldehyde (Scheme 20). When KHMDS in acetonitrile was used as a base in this reaction, a 9 1 mixture of E and Z products was obtained from which the -isomer of integerrinecic acid lactone 46 was isolated in 77% yield. When K2C03/18-crown-6/toluene was employed in a parallel... 

Scheme 9 White and Jayasinghe synthesis of integerrinecic acid lactone...

White and Jayasinghe have reported a synthesis of integerrinecic acid lactone via anchimerically assisted opening of an epoxide [46] (Scheme 71). Ozonolysis of olefin 319, followed by oxidative work-up with Jones reagent, and subsequent... 

The reactions of dimethyl methylphosphonate and the corresponding carbanion in the gas phase have been investigated. The carbanion displays a similar range of reactions to those encountered in solution, including olefmation with carbonyl compounds. The effect on olefin stereochemistry of a variety of conditions in reactions of a-phosphono lactones (e.g. 129) with ethanal and propanal has been studied and the results applied in syntheses of integerrinecic acid and senecic acid lactones. Yet further minor modifications of the conditions for phosphonate-olefination reactions, involving the use of lithium hydroxide as the base, have been reported. ... 

Integerrinecic acid, the diacid derived from a twelve-membered bis-lactonic pyrrolizidine alkaloid, has been synthesized. The ketone (12), obtained by standard cuprate methodology from 2-methylcyclopentanone, is transformed into the diacid (14) via the lactone (13), the yields being between 60 and 80% at each stage (Scheme 9). ... 

Ligularidenecic acid is a hydrolysis product of ligularidine (Table 3 P ii), obtained by Hikichi etal. 133). Structure (71) for this 6-lactone was assigned when it was realised that the physical data were yery similar to those reported earlier for a lactone synthesised by Edwards and Matsumoto 109), as part of their preparation of all the diastereomers of senecic and integerrinecic acids. 

Crotaverric acid is also a 8-lactone, obtained from crotaverrine (Table3Pii) by Suri etal 294). H-N.m.r. spectroscopy showed that crotaverric acid is diastereomeric with the 5-lactone of integerrinecic acid (72). Since lead tetraacetate oxidation of both diacids gave the same ketoacid, it was deduced that crotaverric acid has the opposite stereochemistry to (72) at either C-2 or C-3. 

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