Artemisyl, Santolinyl, Lavandulyl, and Chrysanthemyl Derivatives

Huynh and S. Julia, Synth. Comm., 1977, 7, 103 for the earlier work, see references therein. 

An elegant two-step synthesis of lavandulol (22) consists of the 1,4-addition of lithium dimethylcuprate to the allenic ester (103) followed by prenylation and reduction of the intermediate which is formed.  

Much effort this year has been expended on chrysanthemic acid syntheses. Aratani et al. have extended earlier work on asymmetric synthesis (Vol. 6, p. 21) by decomposing various alkyl diazoacetates in 2,5-dimethylhexa-2,4-diene in the presence of chiral copper complexes to yield up to 92% of rrans-chrysanthemic acid in 88% dextrorotatory enantiomeric excess. Mitra has used ozonolysis of (+)-a-pinene to obtain, stereospecifically, the bromo-ketone (104) which undergoes Favorskii rearrangement to yield the anticipated ester (105) from which (+)-trans-chrysanthemic acid is readily obtained a second paper reports another route from (+)-car-3-ene initially to methyl (—)-c/s-chrysanthemate or to (—)-dihydro-chrysanthemolactone (106), both of which are convertible into (+)-rra s-chrysan- 

Takeda, T. Sakai, S. Shinohara, and S. Tsuboi, Bull. Chem. Soc. Japan, 1977, 50, 1133. 

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Artemisyl, Santolinyl, Lavandulyl, and Chrysanthemyl Derivatives.— The presence of (41) in lavender oil has been reported earlier. Poulter has published the full details of his work (Vol. 5, p. 14) on synthetic and stereochemical aspects of chrysanthemyl ester and alkoxypyridinium salt solvolyses (Vol. 3, pp. 20—22) and discussed its biosynthetic implications. Over 98% of the solvolysis products are now reported to be artemisyl derivatives which are formed from the primary cyclopropylcarbinyl ion (93) which results from predominant (86%) ionization of the antiperiplanar conformation of (21)-)V-methyl-4-pyridinium iodide the tail-to-tail product (96 0.01%) may then result from the suprafacial migration of the cyclopropane ring bond as shown stereochemically in Scheme 3. This is consistent with earlier work (Vol. 7, p. 20, ref, 214) reporting the efficient rearrangement of the cyclobutyl cation (94) to (96) and its allylic isomer, via the tertiary cyclopropylcarbinyl cation (95). ... 

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