Palladium-Catalyzed Hydroboration/Cyclization of 1,n-Dienes

Abstract

While the hydroboration of alkenes is well established, the corresponding cyclization reaction of dienes remains challenging. Here, we report a new method for hydroboration/cyclization applicable to various 1,n-dienes and hydroboranes. The method features the direct synthesis of borylalkyl cyclopentanes from common 1,6-dienes, which is highlighted by syntheses of elaborated pyrrolidine cores from easily accessible diallylamines. Notably, 1,n-dienes (n > 6) also undergo five-membered ring formation, offering "remote" hydroboration/ cyclization that would be otherwise difficult to achieve.

Syntheses, characterizations and catalytic properties of three zinc complexes and one lithium compound chelated by β-diketiminate ligands

“…The alcohols can be further functionalized and converted into halogens and amides or completely converted into amines. Many kinds of complexes, including the main group metals, 49,50 transition metals, [51][52][53] and lanthanide compounds, 54,55 have been used as active catalysts for the hydroboration of unsaturated carbonyl compounds.…”

Conformational Isomerization as a Process to Determine Selectivity over Reaction Pathways: Effect of Alkene Rotation in Chain Walking via Cis Alkene Intermediates

“…Our group has been working on the development of palladium-catalyzed reactions via chain walking. − 1,10-Phenanthroline and its derivatives have mostly been used as ligands in our reactions, such as cycloisomerization and addition/cyclization of 1,n-dienes as well as remote arylative substitution. To gain an understanding of the mechanism, we explored the theoretical investigation of the chain walking process of alkylpalladium species possessing a 1,10-phenanthroline ligand.…”

Theoretical Studies on Relative Stability of Cationic 1,10-Phenanthroline Palladium Complexes Bearing Alkyl Groups by Using Designed Alkane Templates

“…Our group has been developing catalytic organic reactions proceeding via chain walking of 1,10-phenanthroline palladium complexes. − In order to assess the relative stability of the alkyl complexes potentially formed during the chain walking process, we designed two alkane templates, 2-methylpentane and 2-methylhexanes, and conducted theoretical studies on the 1,10-phenanthroline palladium complexes containing 4-methylpentyl and 5-methylhexyl groups and their isomeric structures potentially formed by palladium chain walking (Figure d). These alkane templates are suitable for investigation of the effect of the number of alkyl branches on both (i) the α-carbon directly attached to the palladium center and (ii) the β-carbon agostically interacting with the palladium by the C–H bond.…”