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Please login or sign up for a free trial to access the full content. Method 3: Isomerizing Hydroformylation

DOI: 10.1055/sos-SD-025-00196

Breit, B.Science of Synthesis, (200725293.

Combining alkene isomerization with regioselective hydroformylation of one alkene species preferentially (in general the most reactive, the linear alkene) is referred to as isomerizing hydroformylation and is a hydroformylation variant to provide linear aldehydes from internal alkenes.[‌77‌] Again, especially designed bidentate ligands are essential to achieve useful levels of selectivity. For instance, the rhodiumdiphosphite catalyst 47 (R1=H) system (Scheme 16) converts raffinate 2 (C4 feedstock from the steam cracker consisting of a mixture of C4 alkenes) into pentanol in 94% yield with only 5% 2-methylbutanal and 1% 3-methylbutanal (from isobutene) formed as isomeric products.[‌19‌] The related rhodiumdiphosphite catalyst 47 [R1=(CH2)8Me] allows for an isomerizing hydroformylation of methyl pent-3-enoate (48) to give the linear aldehyde 49 in 91% yield and 85% selectivity.[‌78‌]

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