Freelingyne

Free Electron Molecular Orbital method colour and constitution, 1, 342 Freelingyne occurrence, 4, 706 Free radical processes in photography, 1, 387-389 Friedlander synthesis quinolines, 2, 443 thioindigo dyes, 4, 910 Fries rearrangement chroman-4-one synthesis from, 3, 850 Fructose, 1-deoxy- C NMR, 4, 575 Frusemide as diuretic, 1, 174 metabolism, 1, 245 FS-32 — see 1/f-Indazole, l-[3-... 

Many dozen complex natural products have been synthesized in a highly selective manner by the use of Zr-catalyzed carboalumination of alkynes. Although most of them are not mentioned here due to space limitation, those that have been reported by the author s group over the past few years alone include freelingyne [160], coenzyme Q10 [159], and (3- and y-carotenes [163], which were synthesized with unprecedented efficiency and selectivity. 

Furan-2,5-dione, or maleic anhydride, can quite reasonably be regarded as furanoquinone, the reduced form being furan-2,5-diol. The carbonyl groups do have some ketonic activity, and in Scheme 23 the key step of a second route to freelingyne (86 in Vol. 30) makes use of this capacity in a reaction with another phosphorus ylide reagent.96 (cf. Scheme 16). Even ordinary (carbonyl stabilized) carbanions will undergo such aldol con-... 

It is worthwhile noting that the stereochemistry of the double bond in (31) was assigned from an X-ray study of the a-naphthylurethane derivative. Further stereochemical ambiguity arose in the final step. The reaction between the enyal (32) and the phosphorous ylide gave a 2 3 mixture of isomers, with the minor, and lower polarity, isomer being identical with freelingyne (30). 

The isolation of the bfr-butenolide (38) from a new species of Eremophila provides a likely precursor of freelingnite and freelingyne (35). Its structure was deduced from spectroscopic data, the stereochemistry of the double bond at C-6 being inferred from the well known shielding effect on a methyl carbon by a yn-alkyl group. The configuration of the single asymmetric carbon was... 

A tandem cross-coupling-lactonization between terminal alkyne 19 and Z-iodo acid 20 was anticipated to afford freelingyne, a sesquiterpene from Eremophilia freelingiiP Curiously, presumed free-radical involvement prevented the desired course of reaction. 

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