Six-membered ring systems: diazines and benzo derivatives

Directed Metalation-Cross Coupling Route to Ferroelectric Liquid Crystals with a Chiral Fluorenol Core: The Effect of Intermolecular Hydrogen Bonding on Polar Order

“…The regiochemistry of 15 was confirmed by heteroatom multi-bond correlation (HMBC) NMR (see Supporting Information). The corresponding 5-phenylpyrimidine and 6-phenylpyridazine precursors 18 and 19 were obtained in 77% and 76% yield, respectively, by selective BBr 3 -mediated cleavage of the 4‘-butyloxy groups in mesogens 16 and 17 , which had been prepared in a previous study. , Esterification of the four precursors using DCC/DMAP gave the mesogens BPh , 2-PPy , 5-PPy , and PPz in 79−83% yield. To further assess the effect of hydrogen bonding on mesophase stability and polar order, the fluorenol 3 was methylated using NaH and MeI.…”

Uncatalyzed One-Pot Synthesis of Highly Substituted Pyridazines and Pyrazoline-Spirooxindoles via Domino SN/Condensation/Aza-ene Addition Cyclization Reaction Sequence

“…Pyridazines and fused pyridazines with their reduced derivatives are important subclasses of diaza-six-membered heterocycles that possess synthetic utility − and important pharmacological activities. , Several biologically active natural and unnatural compounds consist of heterocycles containing an N–N bond in six membered rings such as well-known piperazic acid and 1-Azafagomine. − In this class of compounds, 1,4-dihydropyridazines are of particular interest because of their activities as cardiovascular and spasmolytic agents that can be correlated with those of 1,4-dihydropyridine. , Conventional methods for pyridazine synthesis are based on the reaction of hydrazine or its derivatives with 1,4-dicarbonyls − and different types of [2 + 4] hetero Diels–Alder reaction. − Synthetic methods based on Ugi four-component reaction and electrophilic hydrazination of enolates − are most interesting recent methods for the preparation of 1,4-dihydropyridines.…”