Formal (4 + 1)-Addition of Allenoates to <i>o</i>-Quinone Methides
作者:Katharina Zielke、Mario Waser
DOI:10.1021/acs.orglett.7b03906
日期:2018.2.2
The first (4 + 1)-annulation of o-quinonemethides with α-branched allenoates as C1 synthons has been developed. This operationally simple protocol gives access to highly functionalized dihydrobenzofurans in an unprecedented fashion with excellent diastereoselectivities and high yields.
2-Naphthol underwent Friedel-Crafts reaction with N-benzyloxycarbonylamino sulfones in the presence of InCl3 at room temperature to form the corresponding sulfonyl derivatives in high yields. The products were subsequently reacted with nucleophiles such as allyltributyltin and anisole to replace the sulfonyl group.
Chiral diarylmethylamides are a privileged skeleton in many bioactive molecules. However, the enantioselective synthesis of such molecules remains a long-standing challenge in organic synthesis. Herein, we report a chiral bifunctional squaramide catalyzed asymmetric aza-Michael addition of amides to in situ generated ortho-quinomethanes, affording enantioenriched diarylmethylamides in good yields with
ammonium ylides and o-quinone methides for the synthesis of a variety of 2,3-dihydrobenzofurans has been developed. The key factors controlling the reactivity and stereoselectivity were systematically investigated by experimental and computational means and the energy profiles obtained provide a deeper insight into the mechanistic details of this reaction.
efficient [4+3] annulation of 2-(1-tosylalkyl)phenols with C,N-cyclic azomethine imines via in situ generation of ortho-quinone methides (o-QMs) under mild basic reaction condition is disclosed, furnishing biologically interesting seven-membered heterocycliccompounds (on gram scale) with moderate to good yields and excellent diastereoselectivities. A gram-scale reaction is performed to demonstrate the