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2,6-Dibromo-4-methoxy pyridine (6) was obtained in 80% yield when 2,4,6-tribromopyridine (5) was allowed to react with sodium methoxide (1.2 eq) in refluxing methanol. The compound (6) was treated using n-butyl lithium (1.2 eq.), was allowed to react with pivalonitrile (1.2 eq.) for 150 minutes at -78C and was refluxed for two hours in two normal sulfuric acid to yield ketone isomer (7) in 86% yield. An optically active alcohol (8) was obtained in 93% yield and in 90% ee optical purity from compound (7) through hydrogen transfer type asymmetric reduction of formic acid (4.3 eq.) and triethylamine (2.5 eq.) using the asymmetric ruthenium catalyst (RuCl[(S,S]-Tsdpen)(p-cumene), 0.01 eq.) as the catalyst. The compound (8) was converted to a camphor ester using the acid chloride, an optical resolution process was conducted using re-crystallization (75% yield, diastereomer ratio = >99/<1) and saponified again to obtain an almost optically pure alcohol (7, quant.). The compound (7) was subjected to homo coupling using a palladium catalyst [PdCl2(PhCN)2-TDAE] to yield a pyridine isomer (9) (Chemical formula 5) in 36% yield (diastereomer ratio =>99.5/<0.5).
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