Protecting group directed cyclization: asymmetric synthesis of both cis- and trans-dihydrexidine from a common precursor

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• 作者：Rajesh Malhotra ; Sagar Chakrabarti ; Tushar K. Dey ; Swarup Dutta ; Krishna Babu Alapati ; Shantanu Dutta ; Subho Roy ; Sourav Basu ; Saumen Hajra
• 刊名：Tetrahedron
• 出版年：2013
• 出版时间：28 October, 2013
• 年：2013
• 卷：69
• 期：43
• 页码：8994-9000
• 全文大小：569 K

文摘

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 cyclization control the cis-stereochemistry of the B-ring. N-Cbz and O-benzyl protection direct first F-C cyclization yielding the trans-1-aryl-2-aminotetralin and subsequent deprotection-cyclization forming the C-ring afforded dihydrexidine.