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Avenaol, isolated from the allelopathic plant black oat, was the first C20 germination stimulant related to strigolactones. Structurally, it consisted of a bicyclo[4.1.0]heptanone skeleton containing a cyclopropane ring bearing three main chains projecting in the same direction (i.e. all-cis-substituted cyclopropane). Herein, we report the total synthesis of avenaol using a robust strategy involving the formation of an all-cis-substituted cyclopropane via an alkylidenecyclopropane. The key factors in the success of this total synthesis include the Rh-catalysed intramolecular cyclopropanation of an allene, an Ir-catalysed stereoselective double-bond isomerisation, and the differentiation of two hydroxymethyl groups via the regioselective formation and oxidation of a tetrahydropyran based on the reactivity of a cyclopropyl group. This strategy effectively avoids the undesired ring opening of the cyclopropane ring and the formation of a caged structure. Furthermore, this study confirms the proposed structure of avenaol, including its unique all-cis-substituted cyclopropane moiety. [ABSTRACT FROM AUTHOR]

A catalytic method has been developed for construction of indoline-2-thiones containing an all-carbon quaternary centre at the C-3 position. Successive treatment of α, β-unsaturated aldehydes bearing an isothiocyanato moiety with an in situ generated N-heterocyclic carbene and an appropriate heteroatomic nucleophile provided the 3,3-disubstituted indoline derivatives in moderate to good yields. [ABSTRACT FROM AUTHOR]

Synthesis of 3,3-disubstituted 2-aminoindolenines was achieved by palladium-catalyzed allylic amidination with an isocyanide. It was found that isocyanides are effective building blocks in palladium-catalyzed allylic functionalizations, analogous to carbon monoxide. This approach enables the direct construction of the indolenine ring along with the formation of a quaternary carbon and the introduction of an amino substituent in one step under mild conditions. [ABSTRACT FROM AUTHOR]

A new method has been developed for the stereoselective construction of the AB rings of the quinolizidine skeleton of matrine-type alkaloids with a cis-cis stereochemistry. The key features of this method involve: (i) construction of the quinolizidine by reduction of an acylpyridinium cation; and (ii) late-stage introduction of methoxypyridine by sequential Stille coupling and diastereo-selective hydrogenation reactions. [ABSTRACT FROM AUTHOR]