| Cyclic skeletons are broadly distribured in drugs and bioactive natural products. Cycloadditions are one of the most efficient methods for construction such skeletons. Intermolecular cycloadditions and intramolecular cycloadditions are two types of cycloadditions. Atribute to spatial adjacence of the two reactive groups, intramolecular cycloadditions have broader substrate scoupe than intermolecular cycloadditions, and have been widely used to construct polycyclic skeletons in organic synthesis. Most intramolecular cycloadditions reported past were parallel cycloadditions, in which the reactive two groups were connected head to head and tail to tail. The adducts of this parallel cycloadditions are fused cyclic skeletons. We are try our best to develop cross intramolecular cycloadditions in which the reactive two groups are connected head to tail and tail to head. The adducts of this cross cycloadditions are bridged cyclic skeletons. We want to develop new intramolecular cycloaddtions based on cyclopropane1,1-diesters.Firstly, we developed Lewis acids promoted formal intramolecular [3+2] cycloadditions of cyclopropane1,1-diesters with allenes. With different reaction conditions, the parallel cycloadition reaction of1,1-diesters with distal C=C of allene and the cross cycloadition reaction of1,1-diesters with proximal C=C of allene could be realised respectively. Therefore, a general and efficient strategy for construction of structurally diverse [4.3.0]nonane and [3.2.1]octane skeletons was provides. Secondly, we have developed ultraviolet light and Lewis acids co-catalyzed intramolecular [3+2] cross-cycloadditions of cyclopropane1,1-diesters with α,β-unsaturated carbonyls. It provided an efficient method for construction of oxa-[n.2.1] bicyclic skeletons. At last, we have found a cyclization reaction of silyl-alkene and cyclopropane1,1-diesters.There intramolecular cycloadditions and cyclizations provide efficient methodologies for construction complex cyclic skeletons. It will play a key role in organic synthesis and drug discovery. |
