John E. McMurry

A method for the palladium-catalyzed allylic oxidation of olefins

Abstract Olefins are converted into allylic acetates by treatment in acetic acid with a catalytic amount of palladium bis(trifluoroacetate) and one equivalent of benzoquinone as oxidant. The reaction is selective for oxidation of a terminal methyl group of geranylacetone.

An efficient method for the preparation of alkylidenecyclopropanes

Abstract Yields obtained from Wittig reactions with cyclopropylidenetriphenylphosphorane are greatly improved by addition of the phase-transfer catalyst, TDA-1.

A new method of olefin synthesis. Coupling of lithium dialkylcuprates with enol triflates

Abstract Enol trifluoromethansulfonates react with lithium dialkylcuprates to give the coupling products in high yields. The reaction is stereoselective and is successful with a wide variety of organocuprates, including methyl, butyl, phenyl, vinyl, and cyclopropyl reagents.

Synthesis of 1,2-cycloalkanediols by intramolecular titanium-induced pinacol coupling

Abstract Seven representative 1,2-cycloalkanediols of ring size 6-14 were prepared in high yield by titanium-induced pinacol coupling of dialdehydes. Cis stereochemistry predominated in six- and eight-membered rings, but trans products were formed in ring sized ten and above.

Synthesis of helminthogermacrene and β-elemene

Abstract Helminthogermacrene ( 1 ) and β-elemene ( 3 ) have been synthesized by a short route starting from geranylacetone. Titanium-induced cyclization of 3-isopropenyl-6-methyl-10-oxo-6 E -undecenal ( 7 ) was used as the key step.

Stereospecific synthesis of humulene by titanium-induced dicarbonyl coupling

Abstract An efficient stereospecific synthesis of humulene was accomplished using titanium- induced cyclization of 3,37-trimethyl-11-oxoundeca-4 E , 7 E -dienal as the key step.

Synthesis and conformation of unsubstituted calix[4]arene

Abstract The title compound was prepared and its structure was investigated by single-crystal X-ray diffractometry. The conformation of the molecule in the crystalline state was found to be different from those conformations formerly reported for substituted calix[4]arenes. Molecular mechanics calculations indicate that the conformation in the crystal does not represent an energy minimum.

Total synthesis of aphidicolin

Abstract A total synthesis of the antiviral antitumor diterpenoid, aphidicolin (1), is reported. The synthesis starts from the known Δ4-4,10-dimethyioctalin-3,9-dione (5) and requires 15 steps. The two key steps are the Claisen rearrangement of cyclopentenol vinyl ether 16 to unsaturated aldehyde 17, and the carbonylation of unsaturated tosylate 20 to ketone 21. The Claisen rearrangement gives largely cyclopentadiene elimination product under most conditions. We found, however, that thermolysis in the presence of potassium t-pentoxide gives the desired Claisen product 17 in 60% yield. The second key step is carbonylation of 20 with Collmans reagent, disodium tetracarbonylferrate. This reaction, which has not previously been used in natural products synthesis, takes place in 30% yield, and finishes the construction of the aphidicolin skeleton. (±) Aphidicolin was identical with an authentic sample by IR, 1H and 13CNMR, and GC/MS.

Synthesis and stereochemistry of sarcophytol B: An anticancer cembranoid

Abstract A short (5 step), efficient synthesis of sarcophytol B ( 1 ) from farnesal is reported using a low-temperature, titanium-induced pinacol coupling reaction of 1,14-dialdehyde 5 as the key step. An X-ray structure determination showed that sarcophytol B has trans diol stereochemistry.

Synthesis of flexibilene, a naturally occurrring 15-membered-ring diterpene

Abstract A total synthesis of the naturally occurring 15-membered ring diterpene, flexibilene, was accomplished using a titanium-induced cyclization of the keto-aldehyde 3,37,11-tetramethyl- 15-oxohexadeca-4 E ,7 E ,11 E -trienal as the key step.