10064-10-5Relevant academic research and scientific papers
Cyclisation Reactions: Part VI - Further Study in Biogenetic-type Cyclisation of Epoxy-Olefins
Nasipuri, Dhanonjoy,Samaddar, Ashis K.,Das, Gautam
, p. 727 - 734 (2007/10/02)
(6E)-9-p-Methoxyphenyl-2,6-dimethylnona-2,6-diene (I) on mono-epoxidation affords mainly 2,3-epoxyolefin (IV) admixed with some 6,7-isomer.IV on cyclisation with boron trifluoride etherate furnishes three ketones: 7-oxo-9-p-methoxyphenyl-2,6-dimethylnon-2-ene (XIII) presumably formed from 6,7-epoxyolefin (XII), cis-3-(2-p-methoxyphenylethyl)-2,2,4-trimethylcyclohexanone (XIV) arising out of 1,4-hydride transfer in an intermediate cyclohexyl cation (XVII), and cis-3-(2-p-methoxyphenylethyl)-2,3,4-trimethylcyclohexanone (XV) resulting from three consecutive 1,2-H, Me shifts in the same intermediate.In addition, 12-methoxypodocarpa-8,11,13-trien-3β-ol (IX) is obtained in 10 percent yield.The mono-epoxide (V) from the corresponding 3-isopropyl-4-methoxyphenyldiene (II) on similar cyclisation affords, among others, hinokiol methyl ether (X) and another crystalline compound characterised by PMR and MS as 12-methoxy-13-isopropyl-A-homo-4a-oxapodocarpa-8,11,13-trien-3β-ol (XXII).The latter is formed by a concerted cyclisation of the di-epoxide (XXI) present in the starting material.Contrary to a previous report from this laboratory, it is now found that trans-podocarpa-8,11,13-trienes (XXV) are more stable than the cis-isomers and are almost the sole products of cyclisation of 2-(2-arylethyl)-1,3,3-trimethylcyclohexyl cations (XXIV) and their analogues under thermodynamically controlled condition.
