Transition-Metal-Based Synthesis of Dendralenes

The first synthesis of all five possible monomethylated [4]dendralenes has been achieved via two distinct synthetic strategies. The Diels-Alder chemistry of these new dendralenes (as multidienes) with an electron poor dienophile, N-methylmaleimide (NMM), has been studied. Thus, simply upon mixing the dendralene and an excess of dienophile at ambient temperature in a common solvent, sequences of cycloadditions result in the rapid generation of complex multicyclic products. Distinct product distributions are obtained with differently substituted dendralenes, demonstrating that dendralene substitution influences the pathway followed, when a matrix of mechanistic possibilities exists. Dendralene site selectivities are traced to electronic, steric and conformational effects, thereby allowing predictive tools for applications of substituted dendralenes in future synthetic endeavors.

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A General Stereoselective Synthesis of [4]Dendralenes

Fan

Sowden

Magann

et al. 2022

J. Am. Chem. Soc.

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The first general synthesis of branched tetraenes ([4]dendralenes) involves two or three steps from inexpensive, commodity chemicals. It involves an unprecedented variation on Suzuki–Miyaura cross-coupling, generating two new C–C bonds in a one-flask operation with control of diastereoselectivity. The broad scope of the method is established through the synthesis of more than 60 diversely substituted [4]dendralene molecules, along with substituted buta-1,3-dienes and other [n]dendralenes. [4]Dendralenes are demonstrated to be significantly more kinetically stable than their well-known [3]dendralene counterparts. The first stereoselective synthesis of these compounds is also reported, through the catalyst-controlled generation of both E- and Z-diastereomeric products from the same precursor. Novel, through-conjugated/cross-conjugated hybrid molecules are introduced. The first selective dienophile cycloadditions to substituted [4]dendralenes are reported, thus paving the way for applications in target-oriented synthesis.

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Transition-Metal-Based Synthesis of Dendralenes

Abstract: The consecutive ring-closing enyne metathesis of allylsilyl propargyl ethers with Grubbs' ruthenium-alkylidene catalyst, followed by rhenium oxide mediated 1,4-elimination of the Si-O moiety from the siloxenes, provides [3]-and [4]dendralenes in good yields.

Cited by 4 publications

References 7 publications

Formation of Dienes and Polyenes

Formation of Dienes and Polyenes

Synthesis and Diels–Alder Reactivity of Substituted [4]Dendralenes

A General Stereoselective Synthesis of [4]Dendralenes

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