Reductive dehalogenation of alkyl halides with lithium aluminum hydride. Reappraisal of the scope of the reaction

Aluminum-Catalyzed Hydroboration of Alkenes

“…Halide ( 2e ), silyl ( 2f ), and tosyl substituents ( 2g ) were all tolerated without catalyst inhibition or alkene reduction to the alkane, showing the potential for further product functionalization. The successful hydroboration of 1,1-dichloro-2-vinylcyclopropane ( 2h ) proceeded without cleavage of the C–Cl bonds or cyclopropane ring opening . Styrene derivatives bearing both electron-withdrawing and electron-donating functionalities ( 2j – 2p ) all gave good yields and regioselectivities, demonstrating a negligible electronic effect.…”

“…The successful hydroboration of 1,1-dichloro-2-vinylcyclopropane (2h) proceeded without cleavage of the C−Cl bonds or cyclopropane ring opening. 20 Styrene derivatives bearing both electron-withdrawing and electron-donating functionalities (2j−2p) all gave good yields and regioselectivities, demonstrating a negligible electronic effect. Increasing the steric demands of the styrene derivatives NaH (10 mol %) 48…”

Asymmetric Synthesis of Ampelomin A and <i>ent</i>-Epiampelomin A

“…Chemoselective reduction of 5 was readily achieved using LiBH 4 to give a hydroxymethylbicyclolactone that was subsequently derived to the tosylate derivative 8. Typically, reductive removal of a sulfonyloxy group or halogen substituent using hydride reducing agents has been known to be difficult, often requiring harsh reaction conditions, and giving low yields 26,27 . However, LAH reduction of 8 easily removed the tosyloxyl group and reduced the lactone ring at ambient temperature, likely due to the formation of the reactive oxetane intermediate 9 that was immediately opened by the hydride to give 10.…”

Synthesis of Bridged Bicyclic Molecules using Halocarbenes. Derivatives of bicyclo[4.2.1]nonane

“…Calc. C 88.52 H 11.48% Found C 88.49 H 11.56% The endo-configuration was elucidatccl from the fact that 24 was diffcrcnt t o its known exo isomcr 25 [18] 19.112, 10,822 and 5.109 ppm) rcspectivcly with rcspcct to tetramethylsilane taken as 0.000 ppm. [4.2. llnonadienes.…”

“…Reductive Dechlorination. -Two general methods are available for converting organic halides to their parent hydrocarbons : the use of dissolving metals [l'i] or complex metal hydrides [18]. It is well known that the choice of reagent strongly influences the reaction course.…”