74931-59-2Relevant academic research and scientific papers
Commercial manufacturing of propofol: Simplifying the isolation process and control on related substances
Pramanik, Chinmoy,Kotharkar, Sandeep,Patil, Pradip,Gotrane, Dinkar,More, Yogesh,Borhade, Ajit,Chaugule, Balaji,Khaladkar, Tushar,Neelakandan,Chaudhari, Ashok,Kulkarni, Mukund G.,Tripathy, Narendra K.,Gurjar, Mukund K.
supporting information, p. 152 - 156 (2014/05/20)
A commercially viable manufacturing process for propofol (1) is described. The process avoids acid-base neutralization events during isolation of intermediate, 2,6-di-isopropylbenzoic acid (3) and crude propofol, and thus simplifies the synthesis on industrial scale to a considerable extent. Syntheses of five impurities/related substances (USP and EP) are also described.
Expeditious synthesis of benzopyrans via lewis acid-catalyzed C-H functionalization: Remarkable enhancement of reactivity by an ortho substituent
Mori, Keiji,Kawasaki, Taro,Sueoka, Shosaku,Akiyama, Takahiko
supporting information; experimental part, p. 1732 - 1735 (2010/09/05)
An expeditious construction of a benzopyran skeleton via Lewis acid-catalyzed C-H functionalization was achieved. In this process, a [1,5] hydride shift and 6-endo cyclization successively occurred to give benzopyrans. The presence of substituents ortho to the alkoxy group significantly enhanced the reactivity, affording the desired compounds in excellent chemical yields with short reaction times.
Stereoselective ring-opening polymerization of a racemic lactide by using achiral salen- and homosalen-aluminum complexes
Nomura, Nobuyoshi,Ishii, Ryohei,Yamamoto, Yoshihiko,Kondo, Tadao
, p. 4433 - 4451 (2008/02/09)
Highly isotactic polylactide or poly(lactic acid) is synthesized in a ring-opening polymerization (ROP) of racemic lactide with achiral salen- and homosalen-aluminum complexes (salenH2 = N,N′-bis(salicylidene) ethylene-1,2-diamine; homosalenH2 = N,N′-bis(salicylidene) trimethylene-1,3-diamine). A systematic exploration of ligands demonstrates the importance of the steric influence of the Schiff base moiety on the degree of isotacticity and the backbone for high activity. The complexes prepared in situ are pure enough to apply to the polymerizations without purification. The crystal structures of the key complexes are elucidated by X-ray diffraction, which confirms that they are chiral. However. analysis of the 1H and 13C NMR spec tra unambiguously demonstrates that their conformations are so flexible that the chiral environment of the complexes cannot be maintained in solution at 25°C and that the complexes are achiral under the polymerization conditions. The flexibility of the back-bone in the propagation steps is also documented. Hence, the isotacticity of the polymer occurs due to a chain-end control mechanism. The highest reactivity in the present system is obtained with the homosalen ligand with 2.2-dimethyl substituents in the backbone (ArCH=NCH2CMe2CH2N=CHAr), whereas tBuMe2Si substituents at the 3-positions of the salicylidene moieties lead to the highest selectivity (Pmeso,= 0.98; T m = 210°C). The ratio of the rate constants in the ROPs of racemic lactide and L-lactide is found to correlate with the stereoselectivity in the present system. The complex can be utilized in bulk polymerization, which is the most attractive in industry, although with some loss of stereoselectivity at high temperature, and the afforded polymer shows a higher melting temperature (Pmeso = 0.92, Tm up to 189°C) than that of homochiral poly(L-lactide) (Tm = 162-180°C). The "livingness" of the bulk polymerization at 130°C is maintained even at a high conversion (97-98%) and for an extended polymerization time (1-2 h).
A novel dinuclear chiral niobium complex for Lewis acid catalyzed enantioselective reactions: Design of a tridentate ligand and elucidation of the catalyst structure
Kobayashi, Shu,Arai, Kenzo,Shimizu, Haruka,Ihori, Yoichi,Ishitani, Haruro,Yamashita, Yasuhiro
, p. 761 - 764 (2007/10/03)
Two's company: By using a novel chiral ligand a dinuclear chiral niobium catalyst for highly enantioselective Mannich-type reactions was developed. Tridentate binol derivatives provide excellent asymmetric environments around the niobium atom, and the Man
Chiral zirconium catalysts using multidentate BINOL derivatives for catalytic enantioselective Mannich-type reactions; ligand optimization and approaches to elucidation of the catalyst structure
Ihori, Yoichi,Yamashita, Yasuhiro,Ishitani, Haruro,Kobayashi, Shu
, p. 15528 - 15535 (2007/10/03)
Catalytic enantioselective Mannich-type reactions of silicon enolates with aldimines were investigated using chiral zirconium catalysts prepared from Zr(OtBu)4, N-methylimidazole, and newly designed multidentate BINOL derivatives. Th
Enantioselective Total Synthesis of (-)-Triptolide, (-)-Triptonide, (+)-Triptophenolide, and (+)-Triptoquinonide
Yang, Dan,Ye, Xiang-Yang,Xu, Ming
, p. 2208 - 2217 (2007/10/03)
The first enantioselective total synthesis of (-)-triptolide (1), (-)-triptonide (2), (+)-triptophenolide (3), and (+)-triptoquinonide (4) was completed. The key step involves lanthanide triflate-catalyzed oxidative radical cyclization of (+)-8-phenylmenthyl ester 30 mediated by Mn(OAc)9, providing intermediate 31 with good chemical yield (77%) and excellent diastereoselectivity (dr 38:1). (+)-Triptophenolide methyl ether (5) was then prepared in >99% enantiomeric excess (>99% ee), and readily converted to natural products 1-4. In addition, transition state models were proposed to explain the opposite chiral induction observed in the oxidative radical cyclization reactions of chiral β-keto esters 17 (without an α-substituent) and 17a (with an α-chloro substituent).
Investigation of Mn(III)-based oxidative free radical cyclization reactions toward the synthesis of triptolide: The effects of lanthanide triflates and substituents on stereoselectivity
Yang, Dan,Ye, Xiang-Yang,Xu, Ming,Pang, Kwan-Wah,Cheung, Kung-Kai
, p. 1658 - 1663 (2007/10/03)
Mn(III)-mediated oxidative free radical cyclization reactions are useful for construction of polycyclic compounds. In the total synthesis of triptolide (3) and its related compounds, construction of tricyclic skeletons 4 and 5 was achieved by the Mn(OAc)
Synthesis, Biological Evaluation, and Preliminary Structure-Activity Considerations of a Series of Alkylphenols as Intravenous Anesthetic Agents
James, Roger,Glen, John B.
, p. 1350 - 1357 (2007/10/02)
Following our discovery of the intravenous (iv) anesthetic activity of 2,6-diethylphenol in mice, a series of alkylphenols was examined in this species and the most active analogues were further evaluated in rabbits.The synthesis of compounds which were not commercially available was accomplished by adaptations of standard ortho-alkylation procedures for phenols.Structure-activity relationships were found to be complex, but, in general, potency and kinetics appeared to be a function of both the lipophilic character and the degree of steric hindrance exerted by ortho substituents.The most interesting compounds were found in the 2,6-dialkyl series, and the greatest potency was associated with 2,6-di-sec-alkyl substitution.In particular, 2,6-diisopropylphenol (ICI 35868) emerged as a candidate for further development and has subsequently been shown to be an effective iv anesthetic agent in man.
