TY  - JOUR
A1  - Schultze, Christiane
A1  - Schmidt, Bernd
T1  - Ring-closing-metathesis-based synthesis of annellated coumarins from 8-allylcoumarins
JF  - Beilstein journal of organic chemistry
N2  - 8-Allylcoumarins are conveniently accessible through a microwave-promoted tandem Claisen rearrangement/Wittig olefination/cyclization sequence. They serve as a versatile platform for the annellation of five- to seven-membered rings using ring-closing olefin metathesis (RCM). Furano-, pyrano-, oxepino- and azepinocoumarins were synthesized from the same set of precursors using Ru-catalyzed double bond isomerizations and RCM in a defined order. One class of products, pyrano[2,3-f]chromene-2,8-diones, were inaccessible through direct RCM of an acrylate, but became available from the analogous allyl ether via an assisted tandem catalytic RCM/allylic oxidation sequence.
KW  - coumarins
KW  - heterocycles
KW  - isomerization
KW  - olefin metathesis
KW  - ruthenium
Y1  - 2018
U6  - https://doi.org/10.3762/bjoc.14.278
SN  - 1860-5397
VL  - 14
SP  - 2991
EP  - 2998
PB  - Beilstein-Institut zur Förderung der Chemischen Wissenschaften
CY  - Frankfurt, Main
ER  - 
TY  - JOUR
A1  - Schmidt, Bernd
A1  - Riemer, Martin
T1  - Synthesis of Allyl- and Prenylcoumarins via Microwave-Promoted Tandem Claisen Rearrangement/Wittig Olefination
JF  - Synthesis
N2  - Allyl, dimethylallyl, crotyl, and prenyl ethers of various aromatic ortho-hydroxy carbonyl compounds undergo a tandem sequence of Claisen rearrangement, carbonyl olefination, and cyclization upon microwave irradiation in the presence of a stabilized ylide. The products are multiply substituted 6- or 8-allylated or prenylated coumarins (2H-chromen-2-ones).
KW  - aldehydes
KW  - coumarins
KW  - ketones
KW  - microwave irradiation
KW  - olefination
KW  - tandem reaction
KW  - ylides
Y1  - 2016
U6  - https://doi.org/10.1055/s-0035-1560501
SN  - 0039-7881
SN  - 1437-210X
VL  - 48
SP  - 141
EP  - 149
PB  - Thieme
CY  - Stuttgart
ER  -