Highly Enantioselective Rhodium‐Catalyzed Hydrogenation of 2‐(2‐Methoxy‐2‐oxoethyl)acrylic Acid − A Convenient Access of Enantiomerically Pure Isoprenoid Building Blocks

Abstract

Asymmetric catalytic hydrogenation of 2‐(2‐methoxy‐2‐oxoethyl)acrylic acid (5) to give (2S)‐4‐methoxy‐2‐methyl‐4‐oxobutanoic acid [(S)‐6] was studied. An enantiomeric excess of 99.7% ee was achieved with a catalyst formed in situ from [Rh(COD)2]BF4 and the chiral phosphite L2 in 1,2‐dichloroethane as solvent. In addition, enzyme‐catalyzed semi‐saponification of dimethyl 2‐methylsuccinate was investigated. Mono ester (S)‐6 was transformed into a few compounds which can serve as C5‐building blocks in natural product syntheses. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)

Total Syntheses of Amphidinolides B1, B4, G1, H1 and Structure Revision of Amphidinolide H2

“…[a] [72] tert-Butyl(2-iodoethoxy)diphenylsilane: A solution of 2-iodoethanol (10.0 g, 58 mmol), TBDPSCl (17.9 mL, 69.8 mmol) and imidazole (4.7 g, 69.8 mmol) in CH 2 Cl 2 (70 mL) was stirred for 18 h. Water (30 mL) was added and the mixture extracted with CH 2 Cl 2 (2 30 mL), the combined organic phases were dried over Na 2 SO 4 and evaporated, and the crude material purified by flash chromatography (hexanes) to yield the title compound as a white solid (23.0 g, 97 %). Compound 36: nBuLi (1.6 m solution in hexane, 5.6 mL, 8.9 mmol) was added to a suspension of flame-dried LiCl (806 mg, 19.2 mmol) and iPr 2 NH (1.3 mL, 0.96 mmol) in THF at 0 8C.…”

Evaluation of antifungal and antibacterial activities of monoesters of succinic anhydride

“…All the microbes were found to be sensitive towards compound 20 displaying MIC values 2.12-2.32 µg/mL. The study also showed that halogenated esters (12)(13)(14)(15)(16)(17)(18)(19) (1-8, 21-29) microbes were resistant and showed very small zone of inhibition (Table 1), whereas compounds 9-11 were almost inactive. The prepared compounds showed interesting structure activity relationships while exploring their antifungal and antibacterial activity.…”

“…Relatively high activity was observed for compounds with substituent at 2 and 4 position of benzene ring. Highest activity was revealed by halogenated monoesters (12)(13)(14)(15)(16)(17)(18)(19)(20) in general and iodinated monoesters in particular (18)(19)(20). Monoesters having substituents linked through oxygen to benzene ring (1)(2)(3)(4)(5)(6)(7)(8) and (24-29) displayed relatively less activity as compared to halogenated monoesters.…”

“…Literature revealed that natural and synthetic esters of succinic acid had a wide range of applications like industrial, agrochemical and pharmaceutical [4][5][6][7]. Some of these are the treatment of HIV, tumours, as antiseptic agents, antioxidants, as enzyme inhibition, resolving the racemic mixtures and in the synthesis of bioactive compounds [8][9][10][11][12][13][14][15][16].…”

Synthesis of Versatile Building Blocks through Asymmetric Hydrogenation of Functionalized Itaconic Acid Mono‐Esters

“…[2] These bifunctional, enantiomerically pure compounds could thus be transformed into useful building blocks for a range of (pharmaceutically relevant) natural products. [3] Surprisingly, the use of such itaconic acid monoesters in asymmetric hydrogenation research has received only moderate attention [4] and particularly examples of substrates with a carboxylic acid moiety in the conjugated position are rare. [3,4b,5] In addition, the asymmetric hydrogenation of substituted itaconate derivatives has remained relatively unexplored.…”