4471-05-0Relevant articles and documents
Highly Stereoselective Preparation of β-(Organotelluro)acroleins and Facile Stereospecific Synthesis of Conjugated Dienols
Mo, Xue-Sheng,Huang, Yao-Zeng
, p. 3539 - 3542 (1995)
Diorganoditellurides 1 (1a R=n-Bu; 1b R=Ph), by treated with sodium borohydride, reacted with propargylaldehyde to give corresponding β-(organotelluro)acroleins 2 with high (Z)-stereoselectivity in good yields (2a: Z:E=89:11; 2b: pure Z-isomer); Tellurides 3, on treatment with n-BuLi, reacted with carbonyl compounds to afford conjugated dienols with retention of olefin geometry in high yields.
A relay catalysis strategy for enantioselective nickel-catalyzed migratory hydroarylation forming chiral α-aryl alkylboronates
Chen, Jian,Liang, Yong,Ma, Jiawei,Meng, Lingpu,Zhang, Yao,Zhu, Shaolin
supporting information, p. 3171 - 3188 (2021/11/16)
Ligand-controlled reactivity plays an important role in transition-metal catalysis, enabling a vast number of efficient transformations to be discovered and developed. However, a single ligand is generally used to promote all steps of the catalytic cycle (e.g., oxidative addition, reductive elimination), a requirement that makes ligand design challenging and limits its generality, especially in relay asymmetric transformations. We hypothesized that multiple ligands with a metal center might be used to sequentially promote multiple catalytic steps, thereby combining complementary catalytic reactivities through a simple combination of simple ligands. With this relay catalysis strategy (L/L?), we report here the first highly regio- and enantioselective remote hydroarylation process. By synergistic combination of a known chain-walking ligand and a simple asymmetric cross-coupling ligand with the nickel catalyst, enantioenriched α-aryl alkylboronates could be rapidly obtained as versatile synthetic intermediates through this formal asymmetric remote C(sp3)-H arylation process.
Multicatalytic approach to one-pot stereoselective synthesis of secondary benzylic alcohols
Casnati, Alessandra,Lichosyt, Dawid,Lainer, Bruno,Veth, Lukas,Dydio, Pawe?
, p. 3502 - 3506 (2021/05/10)
One-pot procedures bear the potential to rapidly build up molecular complexity without isolation and purification of consecutive intermediates. Here, we report multicatalytic protocols that convert alkenes, unsaturated aliphatic alcohols, and aryl boronic acids into secondary benzylic alcohols with high stereoselectivities (typically >95:5 er) under sequential catalysis that integrates alkene cross-metathesis, isomerization, and nucleophilic addition. Prochiral allylic alcohols can be converted to any stereoisomer of the product with high stereoselectivity (>98:2 er, >20:1 dr).
Homoleptic cobalt(II) phenoxyimine complexes for hydrosilylation of aldehydes and ketones without base activation of cobalt(II)
Hori, Momoko,Ishikawa, Ryuta,Koga, Yuji,Matsubara, Kouki,Mitsuyama, Tomoaki,Shin, Sayaka
supporting information, p. 1379 - 1387 (2021/05/29)
Air-stable, easy to prepare, homoleptic cobalt(II) complexes bearing pendant-modified phenoxyimine ligands were synthesized and determined. The complexes exhibited high catalytic performance for reducing aldehydes and ketones via catalytic hydrosilylation, where a hydrosilane and a catalytic amount of the cobalt(II) complex were added under base-free conditions. The reaction proceeded even in the presence of excess water, and excellent functional-group tolerance was observed. Subsequent hydrolysis gave the alcohol in high yields. Moreover, H2O had a critical role in activation of the Co(II) catalyst with hydrosilane. Several additional results also indicated that the cobalt(II) center acts as an active catalyst in the hydrosilylation of aldehydes and ketones.
