Enantioselective palladium catalyzed allylic substitution of acyloxypyrrolinones by alcohols

Abstract

Table 2 Pd catalyzed nucleophilic substitution of (+)-2a (R 1 = Me) at 70 °C a Entry t/min Conversion b (%) Ee c (%) 1 5 43 90 2 25 91 79 3 40 100 75 a Pd(OAc) 2 + PPh 3 (5%) was used as catalyst, Pr i OH was used as solvent. b The conversion was determined by GC. c The ee of (+)-3a (R 2 = Pr i) was determined by chiral GC.

Determination of the Absolute Configuration of 3-Pyrrolin-2-ones

“…Butoxycarbonyl-5-methyl-3-pyrrolin-2-one (1).The compound has mp 73-74°C; [R]D +145 (c ) 1, CHCl3) (lit 8. colorless oil, [R]D -9.6, c ) 1, CHCl3).…”

5-Acetoxy-1-acetyl-3-pyrrolin-2-one

“…Both enantiomers of this synthon can be enantiomerically purified in high yield by a chemo-enzymatic route (van der Deen et al, 1996) and the absolute configuration can be determined by circular dichroism measurements or from the crystal structure of the corresponding tetracarbonyl iron complex (Cuiper et al, 1999). This acyloxypyrrolinone can, for example, be converted into the N-acyliminium precursor 5-isopropoxypyrrolinone (Goubitz et al, 1996) with retention of configuration by means of a palladium-catalyzed allylic substitution (Cuiper et al, 1998).…”

Enantioselective Rhodium-Catalyzed Isomerization of 4-Iminocrotonates: Asymmetric Synthesis of a Unique Chiral Synthon

“…3–5 Current strategies for preparing enantiomerically-enriched 5-alkoxy-3-pyrrolin-2-ones rely heavily on derivatization of enantiopure starting materials provided by nature (eq 1, Scheme 1) 6 or enzymatic resolution of racemic substrates (eq 2). 7 While these methods are useful, a catalytic asymmetric synthesis of this key building block remains unreported.…”

“…After dihydroxylation of 4e with OsO 4 and NMO, protection of the diol with 2,2-dimethoxypropane and removal of the PMB group with CAN, amide 6 undergoes C-C bond forming reactions with indole and allyltrimethylsilane in the presence of Lewis acids in excellent diastereoselectivities and with no significant loss of enantio-purity. Direct removal of the PMB group of 4e and subsequent acylation provides 9 , which is an effective partner for diastereoselective 1,3-dipolar cycloaddition 3b and Diels-Alder reactions. 6d Compound 5v , which is obtained by dihydroxylation of 4v and subsequent protection, undergoes an intramolecular Friedel–Crafts reaction catalyzed by AuOTf to furnish tetracycle 10 in moderate yield and excellent enantio- and diastereoselectivity.…”