910784-96-2Relevant articles and documents
(Planar-Chiral) Ferrocenylmethanols: From Anionic Homo Phospho-Fries Rearrangements to α-Ferrocenyl Carbenium Ions
Korb, Marcus,Mahrholdt, Julia,Lang, Heinrich
, p. 4028 - 4048 (2017)
The reaction of FcCH2OH with chlorophosphates gave ferrocenyl phosphates FcCH2OP(O)(OR)2 [Fc = Fe(η5-C5H5)(η4-C5H4)], which readily separate into phosphate anions and ferrocenyl carbo-cations. The latter species undergoes consecutive reactions, for example, electrophilic aromatic substitutions. When nitriles, instead of alcohols, are treated with FcLi or tBuLi and chlorophosphates, chiral-pool based ferrocenylimino phosphoramidates Fc-CR=N-P(O)(OR*)2 are formed, which are promising candidates for anionic homo phospho-Fries rearrangements. Moreover, the sterically demanding chiral chlorophosphate with R* enabled oxidative couplings of the imines to form a diferrocenylazine. Similarly, the reaction of Fc–Li with 9-anthrylnitrile produced a 10-ferrocenyl-substituted product, contrary to a reaction at the C≡N functionality. A planar-chiral ortho-P(S)Ph2-functionalized ferrocenylmethanol also gave carbo-cations under acidic conditions. These species can be sulfurized in a unique way giving thio ethers, whereby the in situ formed 1,2-P(S)Ph2,CH2+ ferrocene cation acts as the sulfur and electron source. However, lowering the substrate concentration prevents sulfur migration, resulting in electrophilic substitution reactions with aromatic solvents. Planar-chiral ferrocenylmethyl thio or anisyl derivatives were applied as ligands in Pd-catalyzed Suzuki–Miyaura C,C cross-couplings for the atroposelective synthesis of hindered biaryls with up to 26 % ee at low catalyst loadings (1 mol-% Pd).
Synthesis of substituted helicenes by Ir-catalyzed annulative coupling of biarylcarboxylic acid chlorides with alkynes
Kamikawa, Ken,Den, Hiroakira,Tsurusaki, Akihiro,Nagata, Tomoya,Miura, Masahiro
supporting information, p. 1069 - 1074 (2018/07/29)
A series of substituted [4] and [5]helicenes were synthesized in moderate to good yields by an Ir-catalyzed annulative coupling of biarylcarboxylic acid chlorides with internal alkynes, which involves facile C-H bond cleavage and decarbonylation. The double annulative coupling of 1, 1′:5′, 1″-ternaphthalene- 2, 2″-dicarboxylic acid dichloride with 4-octyne was also accomplished to give rise to an S-shaped double helicene. Unexpectedly, a π-extended benzofluoranthene-merged [5]- helicene was constructed through the annulative coupling and the successive C(aryl)-C(aryl) bond forming reaction when 1, 1′:4′, 1″-ternaphthalene-2, 2″-dicarboxylic acid dichloride was employed as the substrate. The crystal structure and the optical properties of the latter unique product were also investigated.
A Planar-Chiral Phosphino(alkenyl)ferrocene for Suzuki-Miyaura C-C Coupling Reactions
Schaarschmidt, Dieter,Grumbt, Martin,Hildebrandt, Alexander,Lang, Heinrich
supporting information, p. 6676 - 6685 (2016/02/19)
Planar-chiral phosphinoferrocene [Fe(η5-C5H3-1-PPh2-2-(E)-CH=CHPh)(η5-C5H5)] (4) was applied in the presence of palladium in Suzuki-Miyaura couplings for the synthesis of sterically congested biaryls. The catalytic activity arises from homogeneous palladium phosphine complexes, of which the potential pre-catalyst [Pd(4)2Cl2] was characterized structurally. The catalytic system is excellently suited for the synthesis of tri-ortho-substituted biaryls under mild conditions (0.1 mol-%, 50-100 C), whereas its application towards the synthesis of tetra-ortho-substituted biaryls is quite limited. Comparing the performance of the reaction with 4 as catalyst and a range of substrates with differing ortho substituents suggests that transmetalation is rate determining. Complex (Sp)-4 was used in atropselective couplings, wherein enantioenrichments of up to 36 % were achieved. The stereoselectivity depends to some extent on the steric properties of the boronic acids; however, slight changes at the aryl halides influence the enantioselectivity.
