Silver Oxide as a Novel Catalyst for Carbon–Carbon Bond-forming Reactions in Aqueous Media
作者:Masaharu Ueno、Arata Tanoue、Shu Kobayashi
DOI:10.1246/cl.2010.652
日期:2010.6.5
Silver oxide was found to be an excellent catalyst for allylation reactions of allyltributyltins with aldehydes in aqueous media. Despite the very low solubility of silver oxide in the media, the reactions proceeded smoothly, and the catalyst was recovered and reused. When α-methyl-substituted allyltributyltin was used as the nucleophile, the corresponding α-adducts were obtained exclusively in high yields with good anti-selectivity. A reaction mechanism including transmetalation from tin to silver is proposed.
Enantioselective Synthesis of α-Allyl Amino Esters via Hydrogen-Bond-Donor Catalysis
作者:Andrew J. Bendelsmith、Seohyun Chris Kim、Masayuki Wasa、Stéphane P. Roche、Eric N. Jacobsen
DOI:10.1021/jacs.9b05556
日期:2019.7.24
diastereoselec-tive synthesis of α-allyl amino esters. The optimized protocol provides access to N-carbamoyl-protected amino esters via nucleophilic allyla-tion of readily accessible α-chloro glycinates. A variety of useful α-allyl amino esters were prepared-including crotylated products bearing vicinal stereocenters that are inaccessible through enolate alkylation-with high enantioselectivity (up to 97% ee)
Treatment of allylic phosphates with the reagent prepared from n-Bu3SnLi and Et2AlCl or from SnF2 and Et2AlCl affords allyltin compounds which react with aldehydes to produce homoallylic alcohols in good yields. The formation of allyltin compounds requires the catalytic amount of Pd(PPh3)4 and proceeds with inversion of the stereochemistry predominantly.
Palladium- and Platinum-Catalyzed Addition of Aldehydes and Imines with Allylstannanes. Chemoselective Allylation of Imines in the Presence of Aldehydes
Pd(II) or Pt(II) complexes (10 mol %) either at room temperature or at reflux, giving the corresponding homoallylic alcohols 3 in high to good yields. Among the catalysts examined, PtCl2(PPh3)2 gave the best result. No only allyltribitylstannane but also methallyl- and crotyltributylstannane could be utilized in this transition metal catalyzed reaction. Detailed mechanistic studies of the Pd(II)-catalyzed
Catalytic asymmetric allylation of aldehydes with allylic trialkylstannanes was achieved with BINAP•AgOTf complex as catalyst. The chiral silver(I) catalyst was readily prepared by stirring an equimolar mixture of BINAP and silver(I) triflate in THF at room temperature. The allylation of a variety of aromatic and α,β-unsaturated aldehydes resulted in high yields and remarkable enantioselectivities