Synthesis of 2,6-Disubstituted Pyridines by Lithiation of Pyrazolo(1,5-a)pyridines.
作者:Akira MIYASHITA、Yasushi SATO、Sayuri WATANABE、Ken-ichi TANJI、Takeo HIGASHINO
DOI:10.1248/cpb.43.174
日期:——
Lithiation of 3-(4, 4-dimethyl-2-oxazolin-2-yl)pyrazolo[1, 5-a]pyridine (1a) with 2 molar equivalents of n-BuLi followed by reaction with benzaldehyde yielded α-(4, 4-dimethyl-2-oxazolidinylidene)-6-(α-hydroxybenzyl)-2-pyridineacetonitrile (2a). Upon similar treatment of other electrophiles, the corresponding 2, 6-disubstituted pyridines 2 were produced. The formation of the pyridines proceeded through lithiation, reaction with an electrophile, and ring-cleavage of the pyrazole ring.
3-(4, 4-二甲基-2-噁唑啉-2-基)吡唑并[1, 5-a]吡啶(1a)与2摩尔当量的n-BuLi反应后,再与苯甲醛反应,得到了α-(4, 4-二甲基-2-噁唑啉烯基)-6-(α-羟基苄基)-2-吡啶乙腈(2a)。在对其他电亲体进行类似处理时,产生了相应的2, 6-双取代吡啶2。吡啶的形成是通过锂化、与电亲体反应以及吡唑环的开环过程进行的。