Synthesis Of Alkylideneyclopropanes And Studies On The Application Of MCPs In Organic Synthesis

Methylenecyclopropanes (MCPs), which are highly strained but readily available molecules and of syiithetic interest due to the attractive feature of MCPs which have multiple possibilities for reaction of the three strained bonds (two proximal and one distal bonds) in the cyclopropane ring, have been studied.Firstly, the tandem Michael addition-intramolecular acylation of phenols, thiophenols, selenophenols with alkylidenecyclopropyl carboxylic esters was investigated and 4H-l-benzopynin - 4 - ones, 4H-l-benzothiopyran-4-ones, 4H-1-benzoselenopyran - 4 - ones were obtained respectively in moderate yields.Secondly, the tandem Michael addition-intramolecular substitution of selenoamide with 2-bromo-2-cyclopropylideneacetate was investigated and 5-spirocyclopropane-annulated selenazoline-4-carboxylates were synthesized in good yields. By the CuBr2-mediated halogenation reaction, the cyclopropyl group could be opened and two different bromines could be introduced in the molecular. The two different bromines could be further transformed.Thirdly, the Ritter reaction of alkylidenecyclopropanes was investigated and N-[(E)-hornocinnamyl] amides were stereoselectively synthesized in moderate yields in one-pot manner.Fourthly, CuX2-mediated halogenation reaction of alkylidenecyclopropanes afforded Z-2, 4-dihalobutenes highly efficiently and stereoselectively in good yields. Furthermore, Z-2, 4-dihalobutenes could be further transformed and used in the preparation of 4-alkylidene-5, 6-dihydro-4H-pyrrolo[l,2-c][l,2,3]triazoles.Finally, we developed a novel CAN-mediated radical transformation of MCPs with 1,3-dicarbonyl compounds to give the novel [3+2] annulation compounds in moderate to good yields under mild conditions. Furthermore, CAN-mediated ring-rearrangement reaction of MCPs was investigated and cyclobutanone derivatives could be obtained in moderate yields. And a preliminary study of reaction mechanism was carried out.