Catalytic Asymmetric Synthesis of Chiral Allylic Esters

Abstract

A broadly useful catalytic enantioselective synthesis of branched allylic esters from prochiral (Z)-2-alkene-1-ols has been developed. The starting allylic alcohol is converted to its trichloroacetimidate intermediate by reaction with trichloroacetonitrile, either in situ or in a separate step, and this intermediate undergoes clean enantioselective S N 2′ substitution with a variety of carboxylic acids in the presence of the palladium(II) catalyst (R p ,S)-di-μ -acetatobis[(η 5 -2-(2'-(4'-methylethyl) oxazolinyl)cyclopentadienyl,1-C,3'-N)(η 4 -tetraphenylcyclobutadiene)cobalt]dipalladium, (R p ,S)-[COP-OAc] 2 or its enantiomer. The scope and limitations of this useful catalytic asymmetric allylic esterification are defined.

Transition metals in organic synthesis: Highlights for the year 2005

“…A palladiumcatalyzed asymmetric synthesis of allylic esters from (Z)-allylic trichloroacetimidates was developed (Eq. (80)) [642]. Palladium catalyzed a dynamic kinetic resolution of racemic allylic carbonates to give allylic alcohols [643].…”

Synthesis, reactivity and structural studies of (η5-methylcyclopentadienyl)(η4-tetraphenylcyclobutadiene)cobalt and its derivatives

“…The high air and moisture stability of this compound which often surpass ferrocene and the relative ease of its synthesis makes this molecule a potential alternative to ferrocene in many reactions. A few examples of planar chiral derivatives of (g 5 -Cp)Co(g 4 -C 4 Ph 4 ) have already shown promise in enantioselective catalysis such as palladium catalyzed allylic substitutions and rearrangements of allylic trichloroacetimidates and N-(4-methoxyphenyl) trifluoroacetimidates [4][5][6][7].…”

Synthesis of Pentahydroxylated Pyrrolizidines and Indolizidines

“…The spectroscopic data of 13 were identical with those previously reported. 16 (1 0 S,2R,3aR,4R,5R,6R)-4,5-Dibenzyloxy-6-benzyloxymethyl-2-(1,2-diacetyloxyethyl)hexahydropyrrolo [1,2-b]isoxazole (25). A solution of 7 (54 mg, 0.13 mmol) and 12 (60 mg, 0.46 mmol) in anhydrous DCM (0.2 mL) was heated at 70°C under microwave irradiation in a sealed tube with an Ar atmosphere.…”