The effects of phosphorus substituents on the reactivity of α‐alkoxyphosphonium salts with nucleophiles has been explored. Reactions of α‐alkoxyphosphonium salts, prepared from various acetals and tris(o‐tolyl)phosphine, with a variety of nucleophiles proceeded efficiently. These processes represent the first examples of high‐yielding nucleophilic substitution reactions of α‐alkoxyphosphonium salts
Unusual Carbon−Carbon Bond Formations between Allylboronates and Acetals or Ketals Catalyzed by a Peculiar Indium(I) Lewis Acid
作者:Uwe Schneider、Hai T. Dao、Shu̅ Kobayashi
DOI:10.1021/ol100450s
日期:2010.6.4
mechanism is proposed in which a single InI center acts as a dual catalyst to activate both reagents sequentially. Contrary to the classic γ-selectivity of allylsilanes (Hosomi−Sakuraireaction), this InI-catalyzed boronovariant displays distinct α-selectivity. Substrate scope and functional group tolerance proved to be excellent.
在I OTf中,已发现它是有效的路易斯酸催化剂,用于用烯丙基硼酸酯对乙缩醛或缩酮进行前所未有的亲核取代。提出了一种超金属化S N 1机制,其中单个In I中心充当双重催化剂,以依次激活两种试剂。与烯丙基硅烷的经典γ选择性(Hosomi-Sakurai反应)相反,此In I催化的硼烷变体表现出独特的α选择性。底物范围和官能团耐受性被证明是极好的。
Multicomponent Aromatic and Benzylic Mannich Reactions through C−H Bond Activation
作者:Tania Xavier、Corinne Rayapin、Erwan Le Gall、Marc Presset
DOI:10.1002/chem.201903414
日期:2019.10.28
Multicomponent Mannich reactions through C-H bond activation are described. These transformations allowed for the straightforward generation of densely substituted benzylic and homo-benzylic amines in good yields. The reaction involves a reaction between two transient species: an organometallic species, generated by transition-metal-catalyzed sp2 or sp3 C-H bond activation and an in situ generated
A Simple, Efficient and General Procedure for Acetalization of Carbonyl Compounds and Deprotection of Acetals under the Catalysis of Indium(III) Chloride
作者:Brindaban C. Ranu、Ranjan Jana、Sampak Samanta
DOI:10.1002/adsc.200303154
日期:2004.3
Indium(III) chloride efficiently catalyzes the protection of a variety of aldehydes and ketones to their corresponding 1,3-dioxolanes and dialkyl acetals in refluxing cyclohexane. On the other hand, deprotection of acetals is also achieved in refluxing aqueous methanol under the catalysis of indium(III) chloride.
Copper(II) tetrafluoroborate as a novel and highly efficient catalyst for acetal formation
作者:Raj Kumar、Asit K. Chakraborti
DOI:10.1016/j.tetlet.2005.09.168
日期:2005.11
Commercially available copper(II) tetrafluoroborate hydrate has been found to be a highly efficient catalyst for dimethyl/diethyl acetal formation in high yields from aldehydes and ketones by reaction with trimethyl/triethyl orthoformate at room temperature and in short period. Acetalisation was carried out under solvent-free conditions with electrophilic aldehydes/ketones. For weakly electrophilic