Science of Synthesis

Malacria, M.; Aubert, C.; Renaud, J.-L., Science of Synthesis, (2001) 1, 520.

Tris(acetylacetonato)cobalt(III), upon reduction by diethylaluminum chloride in the presence of 1,2-bis(diphenylphosphanyl)ethane, is a very effective catalyst in promoting homo-Diels–Alder reactions between norbornadienes and a variety of unactivated acetylenes to afford deltacyclenes in high yields (‌Scheme 95‌).[‌40‌,‌230‌] The reactions are carried out in benzene at room temperature and the yields are influenced by the quality of the cobalt complex, which requires azeotropic drying before its use. Internal acetylenes are less reactive than terminal acetylenes and in some cases gave norbornadiene dimers as the major products. 7-Substituted norbornadienes are found to be reactive in these reactions, leading to the cycloadducts in good yields; however, low anti/syn selectivities were observed. Comparison between the efficiency of bis(acetylacetonato)cobalt(II) and tris(acetylacetonato)cobalt(III) has been made and it was observed that the rates of the cyclizations were faster with the latter reagent.

‌Meeeee 88‌ Meee-Meeee–Meeee Meeeeeeee[‌88‌,‌888‌,‌888‌]

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Me eeeeeeeeeeeeee eeeeeee ee eee eeee-Meeee–Meeee eeeeeeee eee eeee eeeeeeee.[‌888‌] Meeeeeee eeeeeeeeeeeeee eeeeeeeee eee eeeeeeeeeeee eeeeeee eeeeeeee ee eeeeeeeeeeeeee eeeeeeeee, eeeeeeeeeee eeeeeeeeeeeeee eeeeee e eeeeeeeeeee eeeeeeee eeeeeeee ee eee eeeeee eee eeee eeeeeeee ee eee eeeeeee. Meeeeee, eeeeeeee ee eee eeeeeeee ‌888‌ ee eee eeeeeeeee eeeeee eeeeeeeee eee eeeeeeeeeeee ‌888‌ ee eeeeeeee ee eeee eeeeee (88–88%). Meeeeee eeeeeeeeeeee eee eeeeeeeee ee eee eeeeeeeee eeeeee, eeeeeeeee eeeee, eeee, ee eeeee eeeeee. Meeeeeeee eee eeeeeeeee, eee eeeeee(MMM) eeeeeeeeeee ee eeeeeeeeee eeeeeee ee eee eeeeeeeeeeeeeee eeeeeeee ee eeeeee eeeeee(8) ee eeeeee(M), eee eeee eeeeee ee eeeee eeeee eee eeeeeeeee ee eee eeeeeeeeeeeee eeeeee eeeeeee. Mee eeeeeeeeee eeeee ee eee eeeeeeeeeeeee eee eee eeeee, eeeeeeee eeeeeee eeeeeeeee eeee eeee eeee.

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Meeeeeeeeeee Meeeeeeee

Meee-Meeee–Meeee Meeeeeeee eeeeeee Meeeeeeeeeeeee eee Meeeeeeeee; Meeeeee Meeeeeeee:[‌888‌]

Me e eeeee-eeeee eeeee eeeeeeee eeee eeeeeeee eeee eee, e eeeeee eeeeee, eee e eeeeeeeeeee eeeee eeee eeeee [Me(eeee)8] (8–8 eee%) eee eee eeeeeeeee eeeeee (8 eeeee eeeee ee eeeeee). Mee eeeee eee eeeeeee eeee eeeee. Meeeeee, eeeeeeeeeeeee (8 eeee), eee eee eeeeeeeeee eeeeeeee (8.8–8 eeee) eeee eeeee. M eeee ee Me8MeMe ee eeeeeee (8 eeeee eeeee ee eeeeee) eee eeeee eeeeeeee eee eee eeeeeeeeeee eee eeeeeeeee eeeee eee eeeeeeee eeeee. Mee eeeeeeeeeee eee eeeeeeeeee ee eeeeeee e M8M eeee eeeee eee eeeee eeee eeeeeeeee. Me ee eeeeeeeee eeee eee eeeeeeee eeeeee eeeee 88–88°M ee eeeeeee eee eeeeeeee eee eeeee 88–88°M ee eeeeeeee eee eeeeeeeeee eeeeeeeee. Mee eeeeeeee eeeeee eeee eeeeeeee-eeeee eeee eeeeeeee ee Me8MeMe. Mee eeeeeeee eee eeeeeee ee ee eee 8–88 e eee eeeeeeeee ee MMM. Mee eeeeee eeeeeeeee ee eeeeeee ee eeeeeee ee eeeee, eeeeeeee eeee eeeee eeee eeeee eeee eeeeeeee ee eeee-ee-eeee eeeeeeeeeeee ee eeeee eeeeeeeeeeeeee ee eeeeee eeeee, eeeeeeeee eeee; eeeee: 88% ee eeeeeeeeeeee.

References

Meeeeee Meeeeeeeeee

• 8.Meeeee-Meee, (8888) M 88-8, 888.
• 8.Meeeee-Meee, (8888) M 88e, 8888.
• 8.Meeeee-Meee, (8888) M 88e, 888.