5181-67-9Relevant articles and documents
Synthesis of substituted chrysenes and phenanthrenes
Mitra, Ashutosh,Ghoshe, Swati
, p. 785 - 789 (2007/10/03)
3-Methylchrysene (9a), 2, 3, 9-trimethylchrysene (9b), 2, 6-dimethylphenanthrene (16a) and 1-isopropyl-4,6-dimethylphenanthrene (16b) have been synthesised in the following steps. β-(1-Naphthyl)ethyl bromide (6a), β-(6,7-dimethyl-1-naphthyl)ethyl bromide (6b), β-(3-methylphenyl)ethyl bromide (13a) and β-(2-isopropyl-5-methylphenyl)ethyl bromide (13b) are separately condensed with potassium salt of 1-carbethoxy-4-methylcyclohexane-2-one (1) to give respectively 7a, 7b, 14a and 14b. PPA cyclisation of 7a and 7b affords 8a and 8b while 14a affords 15a and 14b gives a mixture of 15b and 15c. Aromatisation of 8a and 8b leads to 9a and 9b and that of 15a gives 16a while 15b and 15c both produce 16b. The structures assigned are consistent with their spectral data.
Cyclic Ether Formation in Superacid Media
Carr, Graham,Whittaker, David
, p. 359 - 366 (2007/10/02)
The formation of ethers in superacids by interaction of a primary hydroxy group with a carbocation centre has been investigated by a study of cyclisation of suitable substrates, mainly 1-(2-hydroxyethyl)cyclohexanols to give hydrobenzofurans.Cyclisation traps thermodynamically stable ionic species, with rates of reaction dependent upon the size of the ether ring formed.Three- and four-membered ether rings were not formed, five-membered ether rings formed readily, the reaction being comparable in rate with a 1,2-methyl shift.Six-membered rings formed a little less readily and seven-membered rings less readily still, though a yield of 34 percent from a suitable substrate has been recorded.An unexpected feature of the reactions was their stereospecificity; in one case, this is believed to result from a methyl shift concerted with attack of the primary hydroxy group, the reaction proceeding through hindered transition state, in which methyl loss, probably as CH3+, competes with a 1,2-methyl shift.
