Protecting group directed cyclization: asymmetric synthesis of both cis- and trans-dihydrexidine from a common precursor
作者:Rajesh Malhotra、Sagar Chakrabarti、Tushar K. Dey、Swarup Dutta、Krishna Babu Alapati、Shantanu Dutta、Subho Roy、Sourav Basu、Saumen Hajra
DOI:10.1016/j.tet.2013.08.042
日期:2013.10
Protection group of amino- and tethered o-arene functionality of 1,4-aryl-2-amino-1-butanol derived from l-serine dictates the cyclization mode under acidic conditions leading to reverse diastereoselectivity. N-Boc and acetal protected amino alcohol undergo cascade cyclization providing exclusively cis-dihydrexidine via reduction, where formation of C-ring (isoquinoline unit) prior to Friedel–Crafts
保护基团的氨基和系留ö -arene衍生自1,4-芳基-2-氨基-1-丁醇的功能升丝氨酸使然酸性条件导致非对映选择性反转下环化模式。Ñ -Boc和乙缩醛保护的氨基醇进行环化级联提供专门的顺式-dihydrexidine通过还原,其中形成C形环(异喹啉单元)之前的Friedel-Crafts环化控制的顺式-立体化学的B环的。Ñ -Cbz和ö -苄基保护直接第一架F-C环化,得到的反式-1-芳基-2-氨基四氢化萘和随后的脱保护环化形成C形环,得到二羟西汀。