Enantioselective Synthesis of Spiropyrazolone-Fused Cyclopenta[<i>c</i>]chromen-4-ones Bearing Five Contiguous Stereocenters via (3+2) Cycloaddition
作者:Pankaj V. Khairnar、Yin-Hsiang Su、Athukuri Edukondalu、Wenwei Lin
DOI:10.1021/acs.joc.1c01215
日期:2021.9.3
An enantioselectivesynthesis of spiropyrazolone-fused cyclopenta[c]chromen-4-ones is demonstrated via a (3+2) cycloaddition reaction. The reactions of 3-homoacylcoumarins and α,β-unsaturated pyrazolones in the presence of the cinchona-alkaloid derived hydrogen-bonding catalyst provide aforementioned spiropyrazolone-chromenone adducts bearing five contiguous stereocenters, of which one is the spiro
通过 (3+2) 环加成反应证明了螺吡唑酮稠合的 cyclopenta[ c ]chromen-4-ones的对映选择性合成。3-高酰基香豆素与α,β-不饱和吡唑啉酮在金鸡纳生物碱衍生的氢键催化剂存在下反应,得到上述螺吡唑酮-色烯酮加合物,其具有五个连续的立体中心,其中一个是螺环全碳四元立体中心。产率(高达 98%),具有良好到出色的立体选择性(>25:1 dr 和高达 99% ee)。这种一锅法也可以在具有类似功效的克级规模上得到实际证明。
Asymmetric Michael reaction of 3-homoacyl coumarins with chromone-fused dienes toward enantioenriched coumarin chromone skeletons
Asymmetric Michaelreaction of 3-homoacyl coumarins and chromone-fused dienes was developed by employing a chiral squaramide, and a series of coumarin chromone skeletons were furnished in moderate to high yields (up to 99%) and stereoselectivities (up to 98 : 2 dr, 99% ee).