Preparation of chiral indanones and dihydrocoumarins; application to synthesis of (+)-3-(2,6-dimethoxyphenyl) pentanoic acid
摘要:
Chiral beta-aryl carboxylic acids, prepared by Michael addition of organocuprates to chiral unsaturated imides, are transformed into chiral 3-alkyl-4-benzoyloxyindan-1-ones via two intramolecular acylations, with intermediate formation of chiral 3-alkylindanones and corresponding dihydrocoumarins. The 3-(S)-ethyl-4-benzoyloxyindanone is transformed into(+)-3-(S)-(2,6-dimethoxyphenyl)pentanoic acid.
Preparation of chiral indanones and dihydrocoumarins; application to synthesis of (+)-3-(2,6-dimethoxyphenyl) pentanoic acid
摘要:
Chiral beta-aryl carboxylic acids, prepared by Michael addition of organocuprates to chiral unsaturated imides, are transformed into chiral 3-alkyl-4-benzoyloxyindan-1-ones via two intramolecular acylations, with intermediate formation of chiral 3-alkylindanones and corresponding dihydrocoumarins. The 3-(S)-ethyl-4-benzoyloxyindanone is transformed into(+)-3-(S)-(2,6-dimethoxyphenyl)pentanoic acid.
An efficient synthesis of chiral 3-arylindanones via iridium-catalyzed asymmetrichydrogenation of 3-arylindenones has been developed. The reaction showed good compatibility with various functional groups, delivering a variety of 3-arylindanones in excellent yields and with good enantioselectivities. The reaction was also carried out on a gram-scale, delivering the product in quantitative yield. In
Cobalt-Catalyzed Enantioselective Intramolecular Hydroacylation of Ketones and Olefins
作者:Junfeng Yang、Naohiko Yoshikai
DOI:10.1021/ja509919x
日期:2014.12.3
Cobalt-chiral diphoshine catalytic systems promote intramolecular hydroacylation reactions of 2-acylbenzaldehydes and 2-alkenylbenzaldehydes to afford phthalide and indanone derivatives, respectively, in moderate to good yields with high enantioselectivities. The ketone hydroacylation did not exhibit a significant H/D kinetic isotope effect (KIE) with respect to the aldehyde C-H bond, indicating that C-H activation would not be involved in the rate-limiting step.
Catalytic Enantioselective Negishi Reactions of Racemic Secondary Benzylic Halides
作者:Forrest O. Arp、Gregory C. Fu
DOI:10.1021/ja053751f
日期:2005.8.1
This report describes the first enantioselective cross-couplings of racemic secondary benzylic halides, specifically, nickel-catalyzed Negishi reactions of bromides and chlorides. The catalyst components are commercially available and air-stable, and the reaction is not highly oxygen- or moisture-sensitive (it can be set up in the air). The method has been applied to the catalytic enantioselective synthesis of intermediates employed by others in the generation of bioactive compounds (e.g., trikentrin A and an androgen receptor agonist).
A Rotary Molecular Motor Gated by Electrical Energy
作者:Chen-Yi Kao、Hsiu-Feng Lu、Ito Chao、Jye-Shane Yang
DOI:10.1021/ol502946v
日期:2014.12.5
DFT calculations predict that the chiral pentiptycene derivative E-1 possesses distinct rotational potential energy surfaces in the neutral vs the radical anionic (E-1(center dot-)) form such that continued electrochemical switching between E-1 and E-1(center dot-) could lead to a directional rotation of the pentiptycene rotor about the exocyclic C-C bond. The time scale of random Brownian rotation is similar to 10(6) s for E-1 and similar to 170 s for E-1(center dot-) at 150 K, and thus a switching time scale of 0.2 s could readily bias the rotation direction to >99% at 150 K. The synthetic feasibility, line-shape analysis on the VT 1H NMR spectra, and electrochemical redox switching of E-1 are demonstrated.