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High Pressure‐Promoted [2+2] Cycloaddition Reactions of 4‐Methylphenyl 1,2‐Propadienyl Sulfone with Enol Ethers
Author(s) -
Aben René W. M.,
Braverman Samuel,
Scheeren Hans W.
Publication year - 2003
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/ejoc.200390135
Subject(s) - chemistry , cycloaddition , enol , sulfone , regioselectivity , cyclobutene , enol ether , isomerization , double bond , dimethylamine , stereoselectivity , medicinal chemistry , tertiary amine , ether , yield (engineering) , ring (chemistry) , acetal , organic chemistry , catalysis , materials science , metallurgy
Under high pressure conditions, 4‐methylphenyl 1,2‐propadienyl sulfone ( 1 ) and enol ethers ( 6 ) undergo regioselective [2+2] cycloaddition reactions to give (3‐alkoxycyclobutylidene)methyl 4‐methylphenyl sulfones ( 7 ). The cycloaddition reaction has a broad scope with respect to the substituents allowed at the enol ether. The synthetic potential of the obtained cycloadducts is illustrated by a stereoselective addition of dimethylamine to the double bond of 7a and 7b to yield 11a and 11b and by a tertiary amine‐induced double bond isomerisation of 7a and 7b , followed by ring‐opening of the cyclobutene intermediate to yield 1‐alkoxybuta‐1,3‐dienes 12a and 12b . (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)