Cyclization cycloheptane synthesis

B.vi. Synthesis of Cycloheptanes Cyclization of 2-Halo-l,8-nonadienes and Related Compounds... 

TABLE 11. Synthesis of Cycloheptanes Cyclization of Halo-1,7-octadienes and Related Componnds. E=C02Me, E = C02Et... 

The key step in a reported total synthesis of d/-serratenediol involves the acid-catalysed, biogenetic-like cyclization of a polyene with partial structure (23), which gives a mixture of cycloheptanes (24) and (25). When treated with concentrated sulphuric acid and formic acid, (- -)-3,7-dimethylocta-1,6-diene gave 1,4,4-trimethyl-cycloheptane-1-carboxylic acid which was isolated as its methyl ester. 

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