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Total Synthesis of Neo‐Tanshinlactones through a Cascade Benzannulation‐Lactonization as the Key Step
Author(s) -
Ghosh Ketaki,
Karmakar Raju,
Mal Dipakranjan
Publication year - 2013
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/ejoc.201300102
Subject(s) - chemistry , annulation , regioselectivity , total synthesis , cascade , stereochemistry , lithium (medication) , cascade reaction , combinatorial chemistry , organic chemistry , catalysis , chromatography , endocrinology , medicine
Abstract The cascade annulation‐lactonization of phthalides with α‐carboxyfurylacrylates in the presence of lithium hexamethyldisilazide (LiHMDS) provides both convergent and semiconvergent regioselective syntheses of neo‐tanshinlactones in moderate yields. This methodology also offers an avenue for the direct syntheses of hitherto unreported 6‐alkoxycarbonyl‐substituted neo‐tanshinlactones and their heterocyclic analogues. A new synthesis of 4‐alkyl phthalides was developed on the basis of a combination of a Duff reaction and Fürstner cross‐coupling.