One-Pot Synthesis of Pyrimidine-5-Carboxaldehyde and Ethyl Pyrimidine-5-Carboxylate by Utilizing Pyrimidin-5-yl-Lithium

Mesoionic insecticides: a novel class of insecticides that modulate nicotinic acetylcholine receptors

“…The 2‐aminopyridine derivatives are generally prepared either by reductive amination of 2‐amino pyridine, by displacement of halogen from a 2‐halopyridine or by displacement of halogen from the benzylic halomethyl heterocycles, as shown in Scheme . The pyrimidinylmethyl amines were prepared from the 2‐pyrimidine carboxaldehyde by reductive amination …”

“…The pyrimidinylmethyl amines were prepared from the 2-pyrimidine carboxaldehyde by reductive amination. 18,19…”

Robust and Scalable Synthesis of Soai Aldehydes via Improved Barbier‐type Halogen−lithium Exchange

“…The conventional halogen‐lithium exchange of the tert ‐butyl substituted pyrimidine 5 a in THF, with n ‐BuLi added slowly over 15 minutes via syringe pump at −80 °C then quenching with 1.2 equivalents of EtOCHO, unsurprisingly did not yield 1 a (Table 1, entry 1) [2a] . However, the yield of 1 a was improved to 42% by performing the exchange and quench at –95 °C (Table 1, entry 2).…”

“…The yield of 1 a was improved under Barbier‐type conditions to 49%, but unreacted 5 a was also recovered (23%) (Table 1, entry 3), indicating optimization of equivalents was required. The formylation was sensitive to the nature of the formylation reagent; by substituting DMF for EtOCHO the yield of 1 a was significantly reduced to 22% with neither 5 a nor hydro‐debrominated side‐product 8 a isolated (Table 1, entry 4), suggesting a DMF mediated degradation pathway [2a,15] . Increasing the equivalents of n ‐BuLi (1.10 equiv) above EtOCHO (1.05 equiv) decreased the isolated yield of 1 a (38%) and increased the proportion of unreacted 5 a (37%) (Table 1, entry 5), suggesting a need to rigorously control the ratio equivalence between n ‐BuLi and EtOCHO.…”

Eine nahezu ideale asymmetrische Autokatalyse mit (2-Alkinyl-5-pyrimidyl)alkanolen

“…Der Halogenaustausch mit Iodwasserstoffsäure verlief an der 2-Position, und man erhielt 5-Brom-2iodpyrimidin, das mit Alkinen in 80 ± 99 % Ausbeute zu den 2-Alkinyl-5brompyrimidinen gekuppelt wurde. [8] Die Lithiierung des Bromids mit noder tert-Butyllithium und die anschlieûende Formylierung [9] mit Ethylformiat lieferten die 2-Alkinylpyrimidin-5-carbaldehyde in 25 ± 60 % Ausbeute. …”