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CAS 55934-93-5 [(butoxymethylethoxy)methylethoxy]propan-1-olColorless Liquid Hebei Mojin buy - large image2

BOHHClClHFelkin-Anh (Re)disfavouredsyn-pentanedipole-dipolevs.OBClHHClHfavouredOHClHHClH≡OHClHHClH≡ClOHClThe allyl borane reagent reacts through a closed (cyclic) transition state and so weneed to draw a chair-like arrangement of atoms. The first representation shows thereaction proceeding through attack predicted by the Felkin-Anh model. This does notoccur due to the syn-pentane interaction (sterics) or the destabilising alignment of theC–Cl dipoles (electronics). Instead the reaction must proceed through anti-Felkin-Anhattack on the aldehyde ...BOHHClClHFelkin-Anh (Re)disfavouredsyn-pentanedipole-dipolevs.OBClHHClHfavouredOHClHHClH≡OHClHHClH≡ClOHCl... in this arrangement we minimise the syn-pentane interaction (C–Cl eclipses C–H).Once again the hardest part is unravelling the 3D representation into a standardskeletal representation. I have tried to make it easier by highlighting in bold all theatoms in the plane of the paper. Thus you should see that two hydrogens and achloride are on the top face.Note: the reaction could proceed through the polar-Felkin-Anh transition state with thechloride perpendicular to the carbonyl but this is unlikely as the isopropyl group wouldeclipse the other chloride.