Triazole phosphonates. Electrophilic substitution of 1‐substituted‐1H‐1,2,4‐triazoles via lithiated triazole intermediates

Abstract

The metalation chemistry of several 1‐substituted‐1H‐1,2,4‐triazoles has been investigated. When various alkyl groups were incorporated in the 1‐position, lithiation proceeded exclusively at C‐5. The 1‐trityl‐, 1‐methyl‐, and 1‐benzyl‐5‐lithio‐1,2,4‐triazoles were stable at −78° and reacted cleanly with a variety of electrophiles. The 1‐benzyl and 1‐methyl derivatives were synthetically more versatile and could be successfully utilized to prepare several examples of the previously unknown 1,2,4‐triazol‐5‐yl phosphonates.

Investigation of N‐ and C‐Phosphanylation of [1,2,4]Triazolo[4,3‐a]pyridines

“…The corresponding products 13a,b were obtained in the two-step synthesis [21] via lithium derivatives of the starting heterocycles 1a,b (Scheme 7). The reaction proceeded smoothly with good yields of phosphanes 13a,b.…”

Pyrrolidine N-alkylphosphonates and related nucleotide analogues: synthesis and stereochemistry

“…Mass spectra were recorded on a ZAB-EQ (VG Analytical) instrument, using FAB (ionization with Xe, accelerating voltage 8 kV, glycerol and thioglycerol were used as matrices) or on LTQ Orbitrap XL (Thermo Fisher Scientific) instrument for ESI. NMR spectra were measured on a Bruker Avance 600 ( 1 H at 600.1 MHz, 13 …”

“…Thus, a tetrazole phosphonic acid 10 was shown to inhibit multiplication of HSV II, and imidazole, benzimidazole, and benzotriazole phosphonic acids have been evaluated as plant growth factors. 11,12 Besides these compounds, many others, such as the triazole, 13 aziridine, 14 azetidine, 15 pyrazole, 16 and pyrrolidine [17][18][19][20][21][22][23] phosphonates were reported and biologically evaluated. We have recently described prolinol-based nucleoside N-methylphosphonates 24 as a new class of nucleotide analogues with a conformationally flexible N-methylphosphonate moiety.…”

Regio‐ und chemoselektive Metallierung von Arenen und Heteroarenen mit gehinderten Metallamidbasen

“…Beispielsweise sind das 1,3,4-Oxadiazol 329 und das 1,2,4-Triazol 330 besonders anfällig für Zersetzungsreaktionen während des Metallierungsprozesses. [218,219] (0.55 ¾quiv., À40 8C, 1.5 h) zinkiert, wobei das Zinkreagens 340 entsteht, das zu dem trisubstituierten Pyridin 341 umgesetzt wird (80 % Ausbeute; Schema 58). [215] Solche Reaktionen kçnnen leicht im 100-mmol-Maßstab durchgeführt werden.…”