Search

A novel Lewis acid-catalyzed [3+2] intramolecular cross-cycloaddition (IMCC) between aziridine 2,2-diesters and conjugated dienes has been developed. This is the first regiospecific IMCC of intramolecular 1,3-dipolar cycloadditions of azomethine ylides with carbon=carbon double bonds, and supplies a general and efficient strategy for construction of structurally complex and diverse aza-[ n.2.1] skeletons. The [3+2]IMCC could be carried out under mild conditions and in gram scale. More importantly, 3-alkyl-substituted aziridines were also successful. The excellent structural diversity, the facile operation and the versatile post-modifications will support the applications of the [3+2]IMCC in natural products synthesis and drugs discovery. [ABSTRACT FROM AUTHOR]

Aiming to develop efficient and general strategies for construction of complex and diverse polycyclic skeletons, we have successfully developed [4+3]IMPC (intramolecular parallel cycloaddition) of cyclopropane 1,1-diesters with [3]dendralenes. With a combination of the [4+3]IMPC and subsequent [4+ n] cycloadditions, trans-[5.3.0]decane skeleton and its corresponding structurally complex and diverse polycyclic variants could be constructed efficiently. This novel [4+3] cycloaddition reaction mode of donor-acceptor cyclopropanes proceeds as a result of the ring-strain relief of a trans-[3.3.0]octane. We strongly believe that the developed methods will demonstrate potential applications in natural products synthesis and drug discovery. [ABSTRACT FROM AUTHOR]

A novel Lewis acid promoted formal intramolecular [3 + 2] parallel/cross-cycloaddition of cyclopropane 1,1-diesters with allenes has been successfully developed, in which the two CC of allenes were involved respectively. This provides a general and efficient strategy for the construction of structurally diverse [4.3.0]nonane and [3.2.1]octane skeletons. [ABSTRACT FROM AUTHOR]

Abstract: We presented a Lewis acid-catalyzed nucleophilic ring opening of methylenecyclopropane (MCP) 1,1-diesters with propargyl alcohols. Unlike the proximal-bond cleavage mode observed in cases of unactivated MCPs, the intrinsic characteristic of MCP 1,1-diesters gave a regiospecific distal-bond cleavage under attack of propargyl alcohols as nucleophiles. By combining a subsequent intramolecular Conia-ene reaction, 3,5-dimethylenetetrahydropyrans could be obtained in either a stepwise or a one-pot strategy. [ABSTRACT FROM AUTHOR]

Abstract: A highly regioselective tandem 1,3-dipolar cycloaddition of cyclopropene 1,1-diesters with nitrile oxides was described. This reaction supplied a new method for synthesis of polyfunctionalized isoxazole derivatives in moderate to excellent yields under mild conditions. [Copyright &y& Elsevier]

A Lewisacid catalyzed intramolecular [3 + 2] cross cycloadditionof cobalt-alkynylcyclopropane 1,1-diesters with carbonyls has beensuccessfully developed. Together with simple and efficient postcycloadditionsof the cobalt-alkyne moiety, a general and efficient strategy forconstruction of structurally complex and diverse medium-sized skeletonsand related polycycles was supplied successfully. [ABSTRACT FROM AUTHOR]

Abstract: Total synthesis of natural product (±)-bruguierol A was accomplished in 10-steps and with an overall 16.8% yield. The embedded unique 8-oxabicyclo[3.2.1]octane core skeleton in this natural product was constructed via a novel Sc(OTf)3-catalyzed intramolecular [3+2] cycloaddition of cyclopropane, which was developed recently in this laboratory. This general synthetic strategy can be potentially applied to the synthesis of a broad range of structurally related natural products. [ABSTRACT FROM AUTHOR]