22273-29-6Relevant academic research and scientific papers
Bisketene Equivalents as Diels-Alder Dienes
Dissanayake, Isuru,Hart, Jacob D.,Becroft, Emma C.,Sumby, Christopher J.,Newton, Christopher G.
supporting information, p. 13328 - 13333 (2020/09/03)
2,5-Bis(tert-butyldimethylsilyloxy)furans are established as vicinal bisketene equivalents for application as dienes in the Diels-Alder reaction. Cycloaddition with olefinic dienophiles, under exceptionally mild conditions, enables convergent access to highly substituted para-hydroquinones in unprotected form via a one-pot Diels-Alder/ring-opening/tautomerization sequence. The synthesis of para-benzoquinones from acetylenic dienophiles, including benzynes, is also demonstrated, and 2,5-bis(tert-butyldimethylsilyloxy)pyrroles are established as competent dienes for the synthesis of para-iminoquinones. Application in natural product synthesis enables gram-scale access to the neuroprotective agent (±)-indanostatin.
1,4-dimethoxy-1,3-butadiene as a Donor Diene in Diels-Alder Cycloadditions
Hiranuma Hidetoshi,Miller, Sidney I.
, p. 5083 - 5088 (2007/10/02)
The title compound (DMBU) is a useful diene in cycloadditions.Since DMBU is readily obtained in two steps from 1,4-dihydroxy-2-butyne, it should be regarded as an inexpensive and abundant starting material.Diels Alder products were obtained from DMBU and the dienophiles, dimethyl acetylenedicarboxylate, ethyl propiolate, benzyne, fumaronitrile, tetracyanoethene, maleic anhydride, 1,2-dibenzoylethene, diethyl azodicarboxylate, and four 1,4-quinones.The aromatization of some of these products was studied.As determined by gas chromatography and 1H NMR, DMBU is obtained as three isomers Z,Z/Z,E/E,E = (60 +/-3):(34 +/- 3):(6 +/- 2).While the Z,Z form is less reactive, the Z,E and E,E isomers react with tetracyanoethene at rates similar to that of 1-methoxy-1,3-butadiene.
