211875-70-6

Upstream product

• 35225-79-7 dibenzylideneacetone 
• 106-95-6 allyl bromide 

Downstream Products

• 269747-90-2 (+/-)-2-(4''-hydroxy-3''-butenyl)-1,1-bis[(E)-2'-phenylethenyl]cyclopropane 

Relevant academic research and scientific papers

Enantioselective homoallyl-cyclopropanation of dibenzylideneacetone by modified allylindium halide reagents-rapid access to enantioenriched 1-styryl-norcarene

Dibenzylideneacetone (8) reacts with in situ-generated allylindium halide reagents to yield the product of a homoallyl-cyclopropanation reaction: 2-(3″-butenyl)-1,1-bis[(E)-2′-phenylethenyl]cyclopropane (9), which proceeds via step-wise cleavage of the C{double bond, long}O bond and delivery of two allyl fragments from the reagent. A range of enantiomerically enriched ligands have been tested as stoichiometric asymmetric modifiers for this process. Enantiopure compounds such as cinchona alkaloids, ephedra, aminoalcohols and tartaric acid derivatives, which have proven of utility as asymmetric modifiers for the indium-mediated allylation of aldehydes and ketones, were very inefficient in the process 8→9. However, mandelic acid derivatives, in particular mandelates, were found to be of significant potential. The absolute stereochemistry of the cyclopropane 9 has been determined by degradation to 1,1-dicarboxymethyl-2-butylcyclopropane, converging with an independent enantioselective synthesis starting from hexene. Under optimised conditions, viz. using allylindium iodide reagents and working-up with aqueous Na2SO3 to avoid iodine-mediated polymerisation, (S)-9 can be generated in 86% yield and with (S)-methyl mandelate as modifier useful enantiopurity (94/6 er) was observed. The cyclopropane product ((S)-9) undergoes RCM using standard conditions to afford a norcarene unit ((1S,6S)-1-(E)-2′-(phenylethenyl)-bicyclo[4.1.0]hept-2-ene) without loss of enantiopurity.

Highly substituted homoallylvinylcyclopropanes by indium-mediated reaction of α,β-unsaturated ketones and aldehydes with allylic halides

Allylindium reagents, prepared from excess allylic halide (Br or I) and indium metal, react with α,β-unsaturated ketones and aldehydes to give, after aerobic acidic workup, homoallyl-substituted vinylcyclopropanes. This process was explored and developed after a chance discovery arising from a side reaction in an attempted Pd-catalysed process. The structure of the cyclopropane arising from the reaction of bis(p-chlorobenzylidine)acetone was confirmed by X-ray crystallography. Whilst bis-α,β-unsaturated ketones give rise to a single homoallylcyclopropane species, α,β-unsaturated ketones and aldehydes give diastereomeric mixtures whose relative stereochemistry were assigned by NOE experiments. Crotylindium reagents react with good to perfect regioselectivity to afford tetrasubstituted cyclopropanes but prenylindium reagents fail to generate the analogous pentasubstituted rings.

Homoallyl-substituted vinylcyclopropanes from α,β-unsaturated ketones and allylindium derivatives

Simply reversing the order of addition of aqueous acid and Et2O to the Barbier intermediate 1 of the known indium-mediated allylation leads to unprecedented deoxygenative rearrangements [Eq. (a)].