Remarkable Electronic Effect on Rhodium-Catalyzed Carbonyl Additions and Conjugated Additions with Arylmetallic Reagents

The Barbier–Grignard-type arylation of aldehydes using unactivated aryl iodides in water

“…Our ongoing work in Rh-catalysed direct arylation with presynthesized organometallic reagents in water 36,37 led us to believe 1b) were examined, but they all failed to increase the yield of the diphenylmethanol product (Table 1, entries 4-10). We speculated that a more electron-donating ligand may be needed to increase the nucleophilicity of the resulting aryl-Rhodium species.…”

Tuning the reactivity of organotin(IV) by LiOH: allylation and propargylation of epoxides via redox transmetalation

“…Since it is well established that the reagent combination of Pd(0/II)/SnCl 2 /allyl bromide generates allyltrihalo stannane [5], we ascribe the above failure due to the poor nucleophilicity of the allylating agent. Concurrent to this observation, we were enthused with the recent suggestion by Li and co-workers [6] that an alkoxy or hydroxy pendant as in RSn(OH) 3 and RSn(OR 0 ) 3 exerts electron donation to the vacant d-orbital of tin, thereby stabilizing the species and consequently enhancing its reactivity. In view of this we desired to generate the potential allylating agent C 3 H 5 Sn(OH) 3 in non aqueous medium.…”

“…Tagliavini and co-workers [10] proposed the formation of hydrated organotin(IV) cations in aqueous solution of organotin halides. Enhanced reactivity of ArSn(OH) 3 , Ar 3 Sn(OMe), ArBi(OH) 2 over the corresponding halo derivatives in arylation reactions is further noteworthy [6,11]. One may also note that while existence of silanetriols RSi(OH) 3 is fully established (vide isolation and X-ray structure), the analogous stannanetriols still await such confirmation [12].…”

“…LiOH in DMSO-d 6 ; c: allyltrihalostannane generated in-situ from allyl bromide/SnCl 2 /Pd(0) in CDCl 3 ; d: after addition of 3 equiv. LiOH to c; 6 ¼ indicates peaks due to 2 J Sn-H and * denotes peak due to residual proton in DMSO-d 6 . (1 ml) was added followed by Sn(OTf) 2 (21 mg, 0.05 mmol).…”

A Highly Enantioselective and Catalytic Aryl Transfer Reaction Using Mixed Triarylbismuthane and Dialkylzinc Reagents

“…However, the reported transmetallation-type reactions, including the formation of a heterodinuclear complex of triorganobismuth, are few. The reaction with palladium [13] and rhodium [14] complexes, copper salts, [15] aryllithium [16] and alkylsodium [17] reagents was reported. To the best of our knowledge, no reports exist of a metal exchange reaction between dialklyzinc and organobismuth reagents.…”