Substituted triazines and pyrimidines from 1,3,5-triazine and a lithium amidinate, alkyl- or 1-azaallyl

Abstract

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. 1 H NMR spectral data showed that the 1,4-dihydrotriazine 3f in toluene-d 8 was in equilibrium with its 1,2-dihydro tautomer. Heating 3f with EtOH or H 2 O in an acidic medium led to the facile cleavage of a C-Si bond and the formation of EtOTMS or (TMS) 2 O, respectively. The 13 C and 15 N NMR spectral data are compared with those obtained by B3LYP/6-31+G* computations on the model compound NC(H)NCH 2 NCH. Treatment of 1 with the lithium amidinate [Li{N(TMS)C(Ph)NTMS}] 2 or with 1-azaallyllithium [Li{N(TMS)C(Ph)C(H)TMS}(tmen)], [Li{N(TMS)C(Bu t )C(H)TMS}] 2 or [Li{N(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 [Li{N(TMS)C(Bu t )C(H)TMS}] 2 an intermediate was isolated-the thermally unstable [Li{N(TMS)C(H)NC(H)NC(H)C(H)C(Bu t )NTMS}] n 8. 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.

Six‐Membered Heterocycles: Triazines, Tetrazines and Other Polyaza Systems

“…The reaction of 1,3,5-triazines and lithium amidinate, alkyl-or 1-azaallyllithium affords substituted 1,3,5-triazines [651].…”

Carbon‐metalated triazines and tetrazines: Synthesis and reactivity

“…4-Tris(trimethylsilyl)silyl-1,4-dihydro-1,3,5-triazine 197 was prepared by addition of TMS 3 SiLi to the unsubstituted 1,3,5-triazine at low temperature (Scheme 46). [61] Note that compound 197 was thermally stable. [61]…”

NMR Spectroscopic Study of Tautomerism in Solution and in the Solid State

“…Most discriminating were the NH/NH 2 proton signals: 39a: δ(NH 2 ) = 5.30-5.50 ppm and δ(NH) = 12.7 ppm; 39b: δ(NH 2 ) = 6.20 ppm and δ(NH) = 12.10-12.20 ppm. The tautomeric equilibrium of dihydro-1,3,5-triazine derivatives 40 (Scheme 5.31) could be frozen in CDCl 3 solution below 25 • C. The 1,4-dihydro tautomer was in equilibrium with its 1,2-dihydro tautomer, circa 50 : 1 at 25 • C [78]. The tautomers were assigned by 1D NOE NMR spectra [78].…”

“…The tautomeric equilibrium of dihydro-1,3,5-triazine derivatives 40 (Scheme 5.31) could be frozen in CDCl 3 solution below 25 • C. The 1,4-dihydro tautomer was in equilibrium with its 1,2-dihydro tautomer, circa 50 : 1 at 25 • C [78]. The tautomers were assigned by 1D NOE NMR spectra [78]. [79].…”