Search

Abstract: An efficient synthesis of (−)‐pyrido[3,4‐b]homotropane (PHT) as well as (±)‐PHT has been achieved in 7 steps from conveniently available starting materials. Key transformations involve an efficient construction of the core bridged 9‐aza‐[4.2.1]nonane skeleton via a Sc(OTf)3‐catalyzed intramolecular cross [3+2] cycloaddition (IMCC) followed by Krapcho decarboxylation and Barton reductive decarboxylation. The present work supplies a general and efficient strategy for synthesis of other bridged analogues. [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]

An acid-catalyzed domino Meinwald rearrangement of epoxides/intramolecular [3+2] cross-cycloaddition of cyclopropane 1,1-diesters was developed. This supplied a method for the construction of bridged oxa-[ n.2.1] ( n = 3, 4) skeletons. [ABSTRACT FROM AUTHOR]

Carbon bridges: The title reaction has been successfully developed, and applied to the total synthesis of the tetracyclic diterpenoids phyllocladanol and phyllocladene. The method provides an efficient, general, and conceptually new strategy for the construction of structurally complex and diverse [n.2.1] carbocyclic skeletons (see scheme). [ABSTRACT FROM AUTHOR]

Abstract: An activated vinyl cyclopropane reacted with substituted benzaldehydes to afford α-methylene γ-butyrolactones in the presence of DABCO·6H2O. This tandem domino process took place in aqueous media, and was presumably initiated with the ring opening of cyclopropane by the nucleophilic addition of DABCO·6H2O. [Copyright &y& Elsevier]

Cycloadditions Developing efficient and general strategies for construction of skeletally complex and diverse polycyclic skeletons in natural products is important and challenging in organic synthesis. In their Communication on page 1231 ff., Z. Wang and co‐workers demonstrate a [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, bridged trans‐[5.3.0]decane skeleton and its corresponding structurally complex and diverse polycyclic ones are constructed efficiently. This strategy is believed to be of potential importance to natural product 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: Catalyzed by Lewis acids, donor–acceptor cyclopropane 1,1-diesters reacted with enol silyl ethers to afford 1,6-dicarbonyl compounds in moderate to excellent yields. This supplied a mild carbon–carbon bond-forming method from the ring opening of cyclopropanes. A smooth tandem [3+2] cycloaddition/ring opening process has been clearly proved by an independent experiment. [Copyright &y& Elsevier]

The article presents chemical equations for the article "Lewis Acids Promoted Formal Intramolecular [3 + 2] Parallel and Cross-Cycloadditions of Cyclopropane 1,1-Diesters with Allenes" by Z. Wang and colleagues, published in "Organic Letters" in 2013 issue.

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]

Abstract: A novel tandem reaction of vinylcyclopropane ketone with benzaldehyde has been successfully developed. This provides a new method for the preparation of γ-oxo-hexenone derivatives from easily accessible starting materials. [Copyright &y& Elsevier]