Categories: Synthesis of O-Heterocycles >
Synthesis of 2H-pyrans and 2H-benzopyrans
Recent Literature
A
one-pot sequence via a Ag(I)-catalyzed propargyl-Claisen rearrangement of easily accessed propargyl vinyl ethers,
followed by a base-catalyzed isomerization, and 6π-oxaelectrocyclization, leads
to the formation of stable 2H-pyrans.
H. Menz, S. F. Kirsch, Org. Lett.,
2006, 8, 4795-4797.
DABCO-catalyzed reactions of α-halo carbonyl compounds with
dimethyl acetylenedicarboxylate (DMAD) at room temperature gave polysubstituted furans and highly functionalized 2H-pyrans in
good yields.
M. Fan, Z. Yan, W. Liu, Y. Liang, J. Org. Chem., 2005, 70, 8204-8207.
A mild, electrophilic cyclization of substituted propargylic aryl ethers by I2,
ICl, and PhSeBr produces 3,4-disubstituted 2H-benzopyrans in excellent
yields. This methodology tolerates various functional groups, such as methoxy,
alcohol, aldehyde, and nitro groups.
S. A. Worlikar, T. Kesharwani, T. Yao, R. C. Larock, J. Org. Chem., 2007,
72, 1347-1353.
