The overall sequence of Rh(II)-catalysed carbenoid generation, oxonium ylid
e formation and subsequent sigmatropic rearrangement utilising 3-diazo-2H-1
-benzopyran-2,4(3H)-dione in cyclic ethers as solvents has been satisfactor
ily used to achieve the synthesis of several medium- to large-membered poly
oxa macrocycles embodying the coumarin subunit. (C) 1999 Elsevier Science L
td. All rights reserved.