An assisted tandem catalytic transformation of diallyl amines and diallyl ethers into N-aryl pyrroles and furans, respectively, is described. The sequence relies on ring closing metathesis followed by dehydrogenation of the initially formed dihydropyrroles and dihydrofurans. Both steps are Ru-catalyzed, but the sequence requires only one precatalyst, because conversion of the metathesis catalys...

Lewis acid promoted reactions of allylsilanes and allenylsilanes provide access to important building blocks for natural product synthesis.1 For example, trimethylsilylallenes function as propargylic anion equivalents in aldehyde addition reactions (eq 1, Path A).2 If the silicon center is sterically congested, the normal addition pathway is suppressed and functionalized dihydrofurans are produ...

Herein we present the synthesis of the anhydrophytosphingosine jaspine B and three of its stereoisomers using a carbohydrate-derived alkoxyallene in order to obtain the products in enantiopure form. Key step of the reaction sequence is the addition of the lithiated alkoxyallene to pentadecanal, setting the configuration at the later C-2 of the ring system. This reaction step proceeds with moder...

A synthetic procedure, catalysed by Ir(ppy)3 under visible-light irradiation, for the chemodivergent synthesis of 2,3-dihydrofurans (3) or ?,?-unsaturated ketones (7) starting from ?-halo (1) and alkenes (2) has been developed. The mild reaction conditions redox-neutral nature process make it particularly sustainable avoiding use both sacrificial reactants stoichiometric strong oxidants. Carefu...

The [3 + 2] cycloaddition reaction between carbonyl ylides generated from epoxides and alkynes (phenylacetylene, methyl propiolate, methyl but-2-ynoate and methyl 3-phenylpropiolate) to give substituted 2,5-dihydrofurans was investigated. The effect of indium(III) chloride on the outcome of the reaction was studied in the case of phenylacetylene and methyl propiolate. The thermal reaction betwe...

The extremely mild and highly efficient catalytic generation of non-metalated, conjugated acetylides is reported. These acetylides are used to generate enol-protected functionalized propargylic alcohols 1, 1,3-dioxolane compounds 2, or 3,4,5-trisubstituted 4,5-dihydrofurans 4 through serial multibond-forming processes. The method calls for a nucleophile (a tertiary amine or phosphine) as a chem...

The concept of combining heterogeneous transition metal and amine catalysis for enantioselective cascade reactions has not yet been realized. This is of great advantage since it would allow for the recycling of expensive and non-environmentally friendly transition metals. We disclose that the use of a heterogeneous Pd-catalyst in combination with a simple chiral amine co-catalyst allows for hig...