Organometallic, Thermal, and Photochemical Methods

Organometallic, Thermal, and Photochemical Methods. The Simmons-Smith cyclopropanation procedure has now been successfully applied to silyl vinyl ethers and 

OSiMej) under the usual condition results in the silyloxycyclopropane (61). However, by performing the cyclopropanation in the presence of acetyl chloride (60 R = OSiMej, R = H) is converted directly into the cyclopropyl ester (62). The styryl ether (63) does not react under the conditions of the Conia modification but, by employing diethylzinc, cyclopropanation is readily effected. To bring about cyclopropanation of the vinyl ether (60 R = OMe or OEt, R = H) without the formation of significant amounts of 2-alkoxymethylenecyclohexane carefully controlled conditions are necessary. The use of diethylzinc also has the beneficial effect of increasing the product yiel in the reaction between benzobarrelene and di-iodomethane. Although all of the possible products are produced, the anti-tricyclic system (64) is by far the major product (30%). 

With the ready availability of the dispiro[2,0,2,l]heptane (22), (see p. 8), [3]-rotane (65) can be prepared quantitatively by Simmons-Smith cyclopropanation.  

When trans-cyclododecen-3-ol is subjected to CH2l2-Cu/Zn treatment the trans,anti-bicyclotridecane (66) is produced in a highly stereoselective manner. The Simmons-Smith cyclopropanation procedure has also been employed in a new synthesis of (+ )-caryophyllene and in the preparation of the parent cyclohepta[a]acenaphthyl-enyl cation.  

A new synthetic route to cyclopropane derivatives from olefins, which should have wide application, involves the reaction between olefins and giem-dihalogeno-compounds 

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