Photoaddition reactions. II. Photoaddition of dimethyl acetylenedicarboxylate to cyclic ethers

Abstract

The photoinitiated free-radical addition of tetrahydrofuran, 2-methyltetrahydrofuran, 1,4-dioxane, and tetrahydropyran to dimethyl acetylenedicarboxylate is found to give cis and trans 1:1 adducts. The products were isolated and characterized. The reaction has been found to be specific in that the trans adducts predominate over the cis.

The photomediated reaction of alkynes with cycloalkanes

“…In view of the reaction times and yields involved -24 h and 5%, and 14 days and 10%, respectively -it is not surprising that the system has not been revisited for over 30 years. The analogous reaction of saturated ethers with DMAD has also been noted, 24,25 with yields of up to 80% being reported for THF. Although the acetone initiation of the addition of DMAD to cyclic ethers was reported, 24 all of the other reactions of ethers and cycloalkanes involved direct irradiation.…”

“…The analogous reaction of saturated ethers with DMAD has also been noted, 24,25 with yields of up to 80% being reported for THF. Although the acetone initiation of the addition of DMAD to cyclic ethers was reported, 24 all of the other reactions of ethers and cycloalkanes involved direct irradiation. The possible involvement of an anioncation radical pair as an intermediate in the reactions 25 of ethers under such conditions was also considered, but a radical chain mechanism initiated by unidentified agents was in general the preferred mechanistic framework.…”

Unprecedented Noncatalyzed anti-Carbozincation of Diethyl Acetylenedicarboxylate through Alkylzinc Group Radical Transfer

“…The photoinduced addition of cyclic ethers, alcohols, 2,2-dialkyldioxolanes, and cycloalkanes to dimethyl acetylenedicarboxylate (DMAD), usually ends with non stereoselective hydrogen atom abstraction. The addition of adamantane to diethyl acetylenedicarboxylate catalyzed by N -hydroxyphtalimide and Co(II) species under O 2 atmosphere gives the Z and E adducts in a ratio close to 70:30 …”

C-nucleoside studies. Part 7. A new synthesis of showdomycin, 2-β-D-ribofuranosylmaleimide

“…in the presence of palladium chloride and mercuric chloride the diester (4) could be isolated as a pure syrup in SOY0 yield after chromatography. 2 The structure was assigned unambiguously by analysis and spectroscopic data. In particular, the IH n.m.r.…”