Abstract
A dichotomy between the additions of organolithiums and lithium amides to cyclobutenediones is described wherein the former give carbonyl addition products while the latter induce ring opening by enone cleavage via O- to C-lithium transfer. This distinct mode of ring scission gives access to 2-oxobut-3-enamides and tetrasubstituted furans.
Highlights
A dichotomy between the additions of organolithiums and lithium amides to cyclobutenediones is described wherein the former give carbonyl addition products while the latter induce ring opening by enone cleavage via O- to C-lithium transfer
Rearrangements triggered by light usually give rise to 5H-furanones 6 via vinylketene (E)-4,9,10 while those triggered by heat typically proceed via the isomeric vinylketene (Z)-4 and give products determined by the nature of the residue introduced at C4
The versatility and reliability of the chemistry is evident from the frequent deployment of such rearrangements in natural products total synthesis.[5,8]
Summary
A new mode of cyclobutenedione ring opening for the synthesis of 2-oxobut-3-enamides and tetrasubstituted furans† A dichotomy between the additions of organolithiums and lithium amides to cyclobutenediones is described wherein the former give carbonyl addition products while the latter induce ring opening by enone cleavage via O- to C-lithium transfer. This distinct mode of ring scission gives access to 2-oxobut-3-enamides and tetrasubstituted furans.
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