Synthesis and biological activity of novel 1,3-benzoxazine derivatives as K+ channel openers

DOI: 10.1248/cpb.44.734

Source and publish data:

Chemical and Pharmaceutical Bulletin p. 734 - 745 (1996)

Update date:2022-09-26

Topics:

Authors:

Yamamoto, Satoshi

Hashiguchi, Shohei

Miki, Shokyo

Igata, Yumiko

Watanabe, Toshifumi

Shiraishi, Mitsuru

Read Full Text PDF DownLoad Join now for total 90,000,000 free articles

Article abstract of DOI:10.1248/cpb.44.734

A new series of 1,3-benzoxazine derivatives with a 2-pyridine 1-oxide group at C4 was designed to explore novel K⁺ channel openers. Synthesis was carried out by using a palladium(0)-catalyzed carbon-carbon bond formation reaction of imino-triflates with organozinc reagents and via a new one-pot 1,3-benzoxazine skeleton formation reaction of benzoylpyridines. The compounds were tested for vasorelaxant activity in tetraethylammonium chloride (TEA) and BaCl₂-induced and high KCl-induced contraction of rat aorta to identify potential K⁺ channel openers, and also for oral hypotensive effects in spontaneously hypertensive rats. An electron- withdrawing group with the proper shape at C6 and a methyl or halogens group at C7 of the 1,3-benzoxazine nucleus were required for the development of optimal vasorelaxant and hypotensive activity. In particular, 2-(6-bromo-7- chloro-2,2-dimethyl-2H-1,3-benzoxazin-4-yl)pyridine 1-oxide (71) showed more potent vasorelaxant activity (EC₅₀=0.14 μM) against TEA and BaCL₂- induced contraction and longer-lasting hypotensive effects than cromakalim (1).