Cyclization/Hydrogermylation of Functionalized 1,6-Dienes Catalyzed by Cationic Palladium Complexes

Abstract

A 1:1 mixture of the palladium phenanthroline complex (phen)Pd(Me)Cl and NaBAr4 (phen = 1,10-phenanthroline; Ar = 3,5-C6H3(CF3)2) catalyzed the reaction of 4,4-disubstituted 1,6-dienes with trialkylgermanes at 80 °C in 1,2-dichloroethane (DCE) to form R3GeCH2-substituted cyclopentanes in good yield with high trans selectivity.

Diastereoselective Cyclization of 1,5‐Dienes with the C−H Bond of Pyridine Catalyzed by a Cationic Mono(phosphinoamide) Alkyl Scandium Complex

“…The stereochemistry of cis ‐ 5 aa was unambiguously confirmed by NOESY experiments and X‐ray crystallographic analysis of its HPF 6 salt (Table , cis ‐ 5 aa H + with PF 6 omitted) . The formation of a cis ‐cyclization product in the present reaction is in sharp contrast with the cyclization of 1,5‐dienes reported previously by other catalysts, which usually gave the trans ‐substituted cyclopentane derivatives as major products ,. Analogous yttrium complex 2 a ‐Y and lutetium complex 2 a ‐Lu showed rather poor activity under the same conditions (Table , entries 5 and 6).…”

“…In principle, the cyclization of dienes with the C−H bonds of organic compounds is the most straightforward and atom‐efficient route for the construction of C‐substituted carbocyclic molecules. However, the C−H‐activation‐mediated annulation of dienes has not been reported previously, despite extensive studies on diene cyclization combined with various transformations such as silylation, boration, hydrogenation, hydrogermylation, and carbometalation ,. This is probably owing to the lack of a suitable catalyst that shows high activity not only for the C−H activation of an organic compound but also for the cyclization of a diene.…”

“…2b-Sc B(C 6 F 5 ) 3 98 (94) [d] > 98: [2][3][4][5][6][7][8] 2c-Sc B(C 6 F 5 ) 3 96 (93) [d] > 98: [2][3][4][5][6][7][8][9] 2d-Sc B(C 6 F 5 ) 3 25 (20) [d] > 98:2-10 [f] Cp*Sc(Bz) 2 B(C 6 F 5 ) 3 70 (62) [d] > 98: 21 7 11 [f] Cp*Y(Bz) 2 B(C 6 F 5 ) 3 www.chemcatchem.org mide) ligands. In combinationw itha ne quimolar amount of a boron compound such as B(C 6 F 5 ) 3 ,t hesec omplexes (such as 2a-Sc) showedexcellent activity and selectivity for the cis-cyclization of aw ide range of 1,5-dienes with the ortho-C(sp 2 )ÀH bond of pyridines.T his unprecedented transformation constitutes a1 00 %a tom-efficient process toward the assembly of pyridyl-functionalized 1,3-disubstituted cyclopentane derivatives containing monocyclic,b icyclic, spirocyclic, and heterocyclic skeletons from simple 1,5-dienes and pyridines in moderate to excellent yields with high diastereoselectivities.…”

Competing reaction pathways of 3,3,3-trifluoropropene at rhodium hydrido, silyl and germyl complexes: C–F bond activation versus hydrogermylation

“…137,[142][143][144][145][146][147] However, transition-metal mediated hydrogermylations have also been reported. 146,[148][149][150][151][152][153][154][155][156][157][158] Recently, Blanchard and co-workers established a stereoselective hydrogermylation of α-trifluoromethylated alkynes and employed the germylated compounds in subsequent cross-coupling reactions. 158 Note that hydrosilylation reactions of 3,3,3-trifluoropropene with HSiPh 3 yielding 1,1,1-trifluoropropane-3-triphenylsilane were described before using [Rh(H)-(PEt 3 ) 4 ] as a catalyst.…”

Advances in Transition‐Metal‐Catalyzed Hydrogermylation of Alkenes and Alkynes†

“…The catalytic hydrogermylation reactions mainly include the following categories: free radical hydrogermylation initiated by photo‐ [ 32‐33 ] or thermal‐excitation, [ 34‐37 ] peroxides, [ 38‐40 ] organic boron reagents [ 41‐48 ] or others [ 49‐51 ] and transition‐metal‐catalyzed hydrogermylation. [ 9,52‐101 ] Transition‐metal‐catalyzed hydrogermylation has the potential advantages of selectivity control upon catalyst tuning.…”