Allylbenzene ozonide (ABO), a model for polyunsaturated fatty acid (PUFA) ozonides, initiates the autoxidation of methyl linoleate (18:2 ME) at 37 degrees C under 760 torr of oxygen. This process is inhibited by d-alpha-tocopherol (alpha-T) and 2,6-di-tert-butyl-4-methylphenol (BHT). The autoxidation was followed by the appearance of conjugated diene (CD), as well as by oxygen-uptake. The rates of autoxidation are proportional to the square root of ABO concentration, implying that the usual free radical autoxidation rate law is obeyed. Activation parameters for the thermal decomposition of ABO were determined under N2 in the presence of radical scavengers and found to be Ea = 28.2 +/- 0.3 kcal mol-1 and log A = 13.6 +/- 0.2; kd (37 degrees C) is calculated to be (5.1 +/- 0.3) X 10(-7) sec-1. Autoxidation data are also reported for ozonides of 18:2 ME and methyl oleate (18:1 ME).

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The reactions of homopropargyl alcohols with titanium tetrachloride-trimethylaluminum in methylene chloride under mild conditions selectively yield after hydrolysis alkenols of the type HOCH(R)CH2CH=C(R')CH3, R = H, Me, and Et and R' = H, Me, Et, n-Pr, i-Pr, n-C4H9, n-C5Hn, and Ph.Ziegler-Natta polymerization catalysts are remarkably facile and repetitive carbometalating reagents toward alkene and alkyne functionalities. While Z-N reagents have been widely successful in the synthesis of stereoregular polyolefins since the 1950's, relatively little attention has been given to controlling their carbometalating properties in a manner that would extend their usefulness to nonmacromolecular synthetic organic chemistry. As part of our continuing interest in synthetic applications of Z-N reagents,1"4 we recently reported the reaction of 3-hexynl-ol with trimethylaluminum-titanium tetrachloride to give in good yield the single carbometalation derived product, (Z)-4-methyl-3-hexen-l-ol,5 an alkenol used by Corey et al. in the synthesis of d,Z-Cls Cecropia juvenile hormone6 and by Baker et al. in the synthesis of the trial pheromone of the Pharaoh's ant.7,8 In this paper we wish to report further studies on the selective methylation of homopropargyl alcohols with the titanium tetrachloridetrimethylaluminum reagent system. Experimental SectionMaterials. The alkynols were purchased from Parchan and used without further purification except for storage over 3-Á molecular sieves. Titanium tetrachloride and neat trimethylaluminum were obtained from Aldrich and the Ethyl Corp., respectively, and used without purification. Trimethylaluminum and titanium tetrachloride solutions were prepared in a nitrogen-filled Vacuum Atmospheres Dri-Lab. Methylene chloride was redistilled over P2Os under nitrogen before use. All chemistry was performed under nitrogen or argon atmospheres by using syringe techniques to transfer reagents.Procedure for Alkynol Methylations. In a typical reaction, 40 mmol of A1(CH3)3 was transferred by syringe into 75 mL of CH2C12 contained in a 250-mL three-necked round-bottom flask equipped with a gas inlet, rubber septa, and a magnetic stirring bar. Titanium tetrachloride (18 mmol) was transferred by syringe into 50 mL of CH2C12 contained in a 120-mL "pop-bottle", which

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