A novel spirocyclic scaffold accessed via tandem Claisen rearrangement/intramolecular oxa-Michael addition

Abstract

A straightforward access to novel spiro[benzofuran-2,3'-pyrrolidine]-2',5'-diones based on the Rh2(esp)2-catalyzed insertion of carbenes derived from diazo arylidene succinimides (DAS) into the O–H bond of phenols is described. The initial adducts underwent a thermally promoted Claisen rearrangement followed by DABCO-catalyzed intramolecular 5-exo-trig oxa-Michael addition.

Entry to new spiroheterocycles via tandem Rh(II)-catalyzed O–H insertion/base-promoted cyclization involving diazoarylidene succinimides

“…A rich synthetic platform for the design of various types of spiroheterocycles is provided by cyclic diazo compounds [ 10 ]. Recently, we and others have demonstrated the efficient use of diazoarylidene succinimides (DAS, 1 ) in the synthesis of spiro-annulated pyrrolidine-2,5-diones by catalyzed spirocyclizations involving aldehydes [ 11 ], tetrahydrofuran [ 12 – 13 ], and in the O–H insertion/Claisen rearrangement/intramolecular oxa-Michael addition cascade [ 14 ] ( Scheme 1 ).…”

Entry to new spiro heterocycles via tandem Rh(II)-catalyzed O–H insertion – base-promoted cyclization involving diazo arylidene succinimides

“…[6][7][8][9] A rich synthetic platform for the design of various types of spiro heterocycles is provided by cyclic diazo compounds. [10] Recently, we and others have demonstrated the efficient use of diazo arylidene succinimides (DAS, 1) in the synthesis of spiro-annulated pyrrolidine-2,5-diones by catalyzed spirocyclizations involving aldehydes, [11] tetrahydrofuran, [12,13] and in the O-H insertion/Claisen rearrangement/intramolecular oxa-Michael addition cascade [14] (Scheme 1).…”