Substituted triazines and pyrimidines from 1,3,5-triazine and a lithium amidinate, alkyl- or 1-azaallyl
作者:W. Marco Boesveld、Peter B. Hitchcock、Michael F. Lappert
DOI:10.1039/b008681i
日期:——
Treatment of 1,3,5-triazine 1 with an alkyllithium LiR [R = a Me, b Bun, c But, d Ph, e CH2TMS, f CH(TMS)2 or g Si(TMS)3(THF)3] yielded the appropriate 1 ∶ 1 addition product 2a–2g, which upon hydrolysis gave the corresponding mono-substituted dihydro-1,3,5-triazine HNC(H)NC(H)(R)NCH 3a–3g. 1H
NMR spectral data showed that the 1,4-dihydrotriazine 3f in toluene-d8 was in equilibrium with its 1,2-dihydro tautomer. Heating 3f with EtOH or H2O in an acidic medium led to the facile cleavage of a C–Si bond and the formation of EtOTMS or (TMS)2O, respectively. The 13C and 15N NMR spectral data are compared with those obtained by B3LYP/6-31+G* computations on the model compound NC(H)NCH2NCH. Treatment of 1 with the lithium amidinate [LiN(TMS)C(Ph)NTMS}]2 or with 1-azaallyllithium [LiN(TMS)C(Ph)C(H)TMS}(tmen)], [LiN(TMS)C(But)C(H)TMS}]2 or [LiN(TMS)C(Ph)C(TMS)2}(THF)2] yielded 2-phenyltriazine 5, 4-phenylpyrimidine 6, 4-tert-butylpyrimidine 9 or, in poor yield, the new 4-phenyl-5-trimethylsilylpyrimidine 7, respectively. In the case of 1 and [LiN(TMS)C(But)C(H)TMS}]2 an intermediate was isolated—the thermally unstable [LiN(TMS)C(H)NC(H)NC(H)C(H)C(But)NTMS}]n8. A pathway is proposed involving the 1,4-addition of the lithium compound to 1,3,5-triazine 1, followed by a 1,3-trimethylsilyl shift, ring-opening and the formation of a new C–C or C–N bond to form the appropriate aromatic heterocycle.
用烷基锂 LiR [R = a Me、b Bun、c But、d Ph、e CH2TMS、f CH(TMS)2 或 g Si(TMS)3(THF)3]处理 1,3,5-三嗪 1 可得到相应的 1∶1 加成产物 2a-2g,水解后可得到相应的单取代二氢-1,3,5-三嗪 HNC(H)NC(H)(R)NCH 3a-3g。1H NMR 光谱数据显示,甲苯-d8 中的 1,4-二氢三嗪 3f 与其 1,2-二氢同系物处于平衡状态。在酸性介质中用 EtOH 或 H2O 加热 3f,可轻易地裂解一个 C-Si 键,并分别形成 EtOTMS 或 (TMS)2O。13C 和 15N NMR 光谱数据与模型化合物 NC(H)NCH2NCH 的 B3LYP/6-31+G* 计算结果进行了比较。用脒酸锂[LiN(TMS)C(Ph)NTMS}]2 或 1-氮杂烯丙基锂[LiN(TMS)C(Ph)C(H)TMS}(tmen)]、[LiN(TMS)C(But)C(H)TMS}]2 或[LiN(TMS)C(Ph)C(TMS)2}(THF)2]处理 1 得到 2-苯基三嗪 5、分别得到 2-苯基三嗪 5、4-苯基嘧啶 6、4-叔丁基嘧啶 9 或新的 4-苯基-5-三甲基硅基嘧啶 7(收率较低)。在 1 和[LiN(TMS)C(But)C(H)TMS}]2 的情况下,分离出了一种中间体--热不稳定的[LiN(TMS)C(H)NC(H)NC(H)C(H)C(But)NTMS}]n8。提出的途径包括锂化合物与 1,3,5-三嗪 1 的 1,4-加成,然后进行 1,3-三甲基硅转移、开环并形成新的 C-C 或 C-N 键,从而形成适当的芳香杂环。