10.1016/S0040-4039(00)01093-5
The study focuses on the synthesis of (+)-alloyohimbane, a yohimbine alkaloid, using the intramolecular Diels-Alder reaction of N-acylvinyl imidates as a key methodology. This approach provides a rapid entry into cis-fused hexahydroisoquinolones, which are essential for constructing the DE rings of yohimbine alkaloids. The chemicals used in the study include sorbic acid, LDA (lithium diisopropylamide), acid chloride, 2-ethoxy-1-aza-1,3-butadiene, benzene, NaBH3CNBH3 (sodium cyanoborohydride), TFA (trifluoroacetic acid), and various other reagents for the synthesis and transformation of intermediates. These chemicals serve to deconjugate sorbic acid, form the Diels-Alder precursor, effect the cycloaddition to form the cycloaddduct, and subsequently reduce and modify the product to afford the target lactam and ultimately (+)-alloyohimbane. The study also developed a radical-based strategy for synthesizing indoline electrophiles from o-bromoaniline derivatives, which are crucial for the synthesis of substituted indolines and the completion of the alkaloid structure.
10.1021/jm00366a007
The research aimed to synthesize and evaluate a series of 1-(2-pyridinyl)piperazine derivatives for their adrenergic activity, specifically as selective a2-adrenoceptor antagonists. The study used various 2-halo-pyridines and piperazines to synthesize the target compounds. Key chemicals included 2-chloro-3-fluoropyridine, piperazine, N-methylpiperazine, and several other halogenated pyridines. The researchers assessed the in vitro activity of these compounds by measuring their ability to displace [3H]clonidine and [3H]prazosin from membrane binding sites in calf cerebral cortex, which indicated their interaction with a2- and a1-adrenoceptors, respectively. In vivo assays involved antagonism of clonidine-induced mydriasis in rats. The study concluded that several compounds, particularly the 3-fluoro derivative (2b), exhibited higher potency and selectivity for a2-adrenoceptors compared to reference standards like yohimbine and rauwolscine. The research suggests that these pyridinylpiperazines could serve as potential therapeutic agents for conditions involving a2-adrenoceptor modulation.
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