作者:G. Subramaniam、R. K. Gilpin
DOI:10.1055/s-1992-35683
日期:——
Hitherto unreported 2′,3′′′′-dimethyl-p-sexiphenyl (6) is synthesized by an unambiguous route in good yield, starting from inexpensive commercially available biphenyl. The general reaction sequence consists of: (i) bischloromethylation of biphenyl, to give 4,4′-bis(chloromethyl)biphenyl (1) (ii) conversion of 1, to its bisphosphonium salt 2 (iii) a Wittig reaction of the salt with two equivalents of β-methylcinnamaldehyde to yield hitherto unreported 4,4′-bis(3-methyl-4-phenyl-buta-1,3-dienyl)biphenyl (3) (iv) the [4 + 2] cycloaddition of 3 with diethyl acetylenedicarboxylate to yield 4 (v) hydrolysis of 4 to 5 (vi) and oxidative decarboxylation of 5 with potassium hexacyano ferrate(III). All reactions which are simple and straightforward proceed in good yield, except the last step.
迄今尚未报道的 2′,3′′′′-二甲基-对-六联苯 (6) 是以廉价的市售联苯为原料,通过明确的路线合成的,收率很高。一般反应顺序包括(i) 联苯的双氯甲基化,得到 4,4′-双(氯甲基)联苯 (1) (ii) 将 1 转化为其双膦盐 2 (iii) 将该盐与两当量的δ-甲基肉桂醛进行维蒂希反应,得到迄今尚未报道的 4、4′-双(3-甲基-4-苯基-丁-1,3-二烯基)联苯 (3) (iv) 3 与乙炔二甲酸二乙酯发生[4 + 2]环加成反应,生成 4 (v) 4 水解生成 5 (vi) 5 与六氰合铁酸钾(III)发生氧化脱羧反应。除最后一步外,所有简单直接的反应都能以良好的收率进行。