Pyrazolo[3,4-b]pyridines. The preparation of 1-protected-1H-pyrazolo[3,4-b]pyridines and attempts to remove the 1-substituent. Some reactions of 1-benzyl-1H-pyrazolo[3,4-b]pyridine and its 7-oxide
作者:Roderick J. J. Dorgan、John Parrick、Christopher R. Hardy
DOI:10.1039/p19800000938
日期:——
conditions gave only the 1H-pyrazolo[3,4-b]pyridin-6(7H)-one isomer [e.g. (14) and (20), respectively]. N-Oxidation of 1-benzyl-1H-pyrazolo[3,4-b]pyridine (4) gave the 7-oxide (21) which yielded (20) and the less usual β-substitution product (22) with acetic anhydride. Nitration of either (4) or (21) gave only substitution at the para-position of the 1 -benzyl substituent, but bromination or chlorination
1-保护的-1 H-吡唑并[3,4- b ]吡啶[例如。(4)]和-1 H-吡唑并[3,4- b ]吡啶-6(7 H)-一[例如。(14)]是从1-取代的5-氨基吡唑类[例如。(1)],并且已经研究了保护基的去除。在酸性条件下用乙酰乙酸乙酯将1-取代的5-氨基吡唑或在相同条件下用β3-氨基丙酸衍生物(19)环合,仅得到1 H-吡唑并[3,4- b ]吡啶-6(7 H)。) -酮异构体[例如。(14)和(20)]。ñ对1-苄基-1 H-吡唑并[3,4- b ]吡啶进行氧化(4),得到7-氧化物(21),得到(20)和较不常见的β-取代产物(22)与乙酸酐。(4)或(21)的硝化仅在1-苄基取代基的对位给出取代,但是溴化或氯化在杂环的3-位给出取代。