Aqueous ZnCl₂ Complex Catalyzed Prins Reaction of Silyl Glyoxylates: Access to Functionalized Tertiary α-Silyl Alcohols

Abstract

An efficient Prins reaction of silyl glyoxylates in the presence of an aqueous ZnCl 2 complex as a catalyst was developed, providing functionalized tertiary α-silyl alcohols in high yields under mild conditions. A preliminary investigation indicated that the aqueous ZnCl 2 complex acted as a dual functional catalyst of Brønsted and Lewis acid to activate the carbonyl groups of silyl glyoxylates via a dual-activation model.

Direct synthesis of branched amines enabled by dual-catalyzed allylic C─H amination of alkenes with amines

“…The final styrene derivatives were purified by column chromatography using silica gel with hexanes/ethyl acetate eluents. The spectroscopic characterization for the alkenes matched those reported in the literature (64)(65)(66)(67)(68)(69)(70)(71)(72)(73)(74)(75)(76).…”

Bimetallic tandem catalysis-enabled enantioselective cycloisomerization/carbonyl–ene reaction for construction of 5-oxazoylmethyl α-silyl alcohol

“…S3 in the ESI for details †). 7 Based on the above experimental results, the absolute conguration of the product and the X-ray single-crystal structure of N,N ′ -dioxide/Co(II) complex, a Unless otherwise noted, all reactions were performed with IPrAuCl/ AgNTf 2 (1 : 1, 5 mol%), Co(OTf) 2 /L 3 -PiPr 2 (1 : 1, 10 mol%), A1-A12 (0.10 mmol), B1 (0.12 mmol) in DCM (1.0 mL) at 35 °C. b Yield of the isolated product.…”

“…Nevertheless, to the best of our knowledge, although remarkable advances concerning the substance scope of aldehydes and activated ketones have been achieved, few examples of acylsilanes are found, which is highly challenging due to the low reactivity arising from the steric and electron-donating effects of the bulky trisubstituted silyl (Scheme 1b). 7 Meanwhile, side reactions may occur, including competing [1,2]-Brook rearrangement 3 e ,4 f ,8 and possible generation of carbenes 4 f , p ,9 from acylsilanes. On the other hand, in view of the importance of the oxazole skeleton, 10 we envisioned that the carbonyl–ene reaction of alkylideneoxazoline with acylsilanes may be favorable by means of the driving aromatization of the former and the assistance of a chiral Lewis acid catalyst lowering the LUMO energy of the latter.…”

HFIP as Protonation Reagent and Solvent for Regioselective Alkylation of Indoles with All-Carbon Centers

“…All reagents were purchased from Sigma-Aldrich and used without further purification unless otherwise noted. The substrates 2d , 2e , 2k , 2f – 2h , 2i , and 2j and 1-allyl-1 H -indole were prepared according to the literature procedures.…”