32174-46-2Relevant academic research and scientific papers
The efficient synthesis of alkoxy-esters from hydroxy carboxylic acids using dimsyllithium in dimethylsulfoxide followed by alkylation with an alkyl halide
Page, Philip C. Bulman,Chan, Yohan,Heaney, Harry,McGrath, Matthew J.,Moreno, Eduardo
, p. 2606 - 2608 (2004)
Hydroxy acids are converted directly into the related alkyl ether-alkyl esters in high yields in a single operation by double deprotonation using dimsyllithium in dimethylsulfoxide followed by treatment with an alkyl halide.
N-SUBSTITUTED ALPHA-AMINO AND ALPHA-HYDROXY CARBOXAMIDE DERIVATIVES
-
Paragraph 130-131, (2021/10/30)
Disclosed are N-substituted α-amino and α-hydroxy carboxamides, pharmaceutical compositions comprising them, and methods of using them.
Silylium-Catalyzed Carbon–Carbon Coupling of Alkynylsilanes with (2-Bromo-1-methoxyethyl)arenes: Alternative Approaches
Rubial, Belén,Ballesteros, Alfredo,González, José M.
, p. 6194 - 6198 (2018/07/31)
The catalytic activation of alkynylsilanes towards 2-halo-1-alkoxyalkyl arenes gives β-halo-substituted alkynes. It involves the chemoselective substitution of an alkoxide by an alkyne in the presence of a neighboring C(sp3)–Br bond in a cationic C–C bond-forming event. Two complementary protocols to accomplish this new transformation are reported. The outcome of a direct approach based on mixing the precursors with a freshly prepared solution of the active catalytic species (TMSNTf2) is compared with an alternative based on smooth release of the required silylium ions upon selective activation of the alkyne by gold(I) (JohnPhosAuNTf2). The two approaches gave satisfactory results to access this otherwise elusive alkynylation process, which furnishes 4-bromo-substituted alkynes and tolerates various functional groups.
Highly efficient and chemoselective zinc-catalyzed hydrosilylation of esters under mild conditions
Kovalenko, Oleksandr O.,Adolfsson, Hans
supporting information, p. 2785 - 2788 (2015/02/05)
A mild and highly efficient catalytic hydrosilylation protocol for room-temperature ester reductions has been developed using diethylzinc as the catalyst. The methodology is operationally simple, displays high functional group tolerance and provides for a facile access to a broad range of different alcohols in excellent yields.
Sensing remote chirality: Stereochemical determination of β-, γ-, and δ-chiral carboxylic acids
Tanasova, Marina,Anyika, Mercy,Borhan, Babak
supporting information, p. 4274 - 4278 (2015/04/14)
Determining the absolute stereochemisty of small molecules bearing remote nonfunctionalizable stereocenters is a challenging task. Presented is a solution in which appropriately substituted bis(porphyrin) tweezers are used. Complexation of a suitably derivatized β-, γ-, or δ-chiral carboxylic acid to the tweezer induces a predictable helicity of the bis(porphyrin), which is detected as a bisignate Cotton Effect (ECCD). The sign of the ECCD curve is correlated with the absolute stereochemistry of the substrate based on the derived working mnemonics in a predictable manner.
The diastereoselective formation of tetraalkoxy[4]resorcinarenes derived from (-)-(2R)-2-methoxy-2-phenylethanol and proof of absolute configurations
Bulman Page, Philip C.,Chan, Yohan,Heaney, Harry,McGrath, Matthew J.,Moreno, Eduardo
scheme or table, p. 5347 - 5354 (2011/11/13)
The preparation of optically pure (-)-3-[(2R)-2-methoxy-2-phenylethoxy] phenol from resorcinol monobenzoate and its conversion into diastereoisomeric tetraalkoxyresorcin[4]arenes together with proof of the absolute configurations of the products is reported. The results of the study indicate that diastereoselective ring closure of linear tetrameric intermediates is controlled by the steric demand of the alkyl group in the precursor 3-alkoxyphenol.
Kinetic resolution of (R,S)-pyrazolides containing substituents in the leaving pyrazole for increased lipase enantioselectivity
Wang, Pei-Yun,Wu, Chia-Hui,Ciou, Jyun-Fen,Wu, An-Chi,Tsai, Shau-Wei
experimental part, p. 113 - 119 (2011/02/21)
With hydrolysis of (R,S)-azolides in water-saturated methyl tert-butyl ether (MTBE) via Candida antarctica lipase B (CALB) as the model system, (R,S)-pyrazolides containing a leaving 3-, 4- or 3,4-substituted-pyrazole moiety are selected as the best substrates for preparing various optically pure carboxylic acids containing an α-chiral center. Great improvements of enzyme activity for the (R)-enantiomers with excellent enantioselectivity (VR/VS > 100) are obtainable, if (R,S)-pyrazolides containing a leaving 3- or 3,4-substituted-pyrazole moiety are employed for the hydrolysis or alcoholysis by methanol in anhydrous MTBE. A detailed kinetic analysis for (R,S)-N-2-phenylpropionylpyrazoles indicates that a bulky 3-substituent such as 3-(3-bromophenyl) or 3-(2-pyridyl) in the leaving pyrazole moiety has profound effects on decreasing the nucleophilic attack and proton transfer of catalytic serine for the slow-reacting enantiomer in anhydrous MTBE, as well as that and substrate affinity for both enantiomers in water-saturated MTBE. The resolution platform is also successfully applied to the hydrolysis of (R,S)-pyrazolides in water-saturated cyclohexane via Candida rugosa lipase (Lipase MY) having opposite enantioselectivity to CALB.
Chiral induction by Cinchona alkaloids in the rhodium(II) catalyzed O-H insertion reaction
Saito, Hiroaki,Iwai, Ryo,Uchiyama, Taketo,Miyake, Muneharu,Miyairi, Shinichi
scheme or table, p. 872 - 874 (2010/09/04)
Cinchona alkaloids are effective additives for enantioselective O-H insertion of α-phenyldiazoacetate and water by rhodium(II) complexes. Addition of silica gel promotes O-H insertion in the reaction rate and the reaction proceeds smoothly at less than the freezing point of water, e.g., -10°C, and provided mandelate in up to 50% ee. The results reported here are the highest asymmetric inductions obtained to date for O-H insertions via a Rh-carbenoid.
Enantioselective iron-catalysed O-H bond insertions
Zhu, Shou-Fei,Cai, Yan,Mao, Hong-Xiang,Xie, Jian-Hua,Zhou, Qi-Lin
experimental part, p. 546 - 551 (2010/10/04)
The ready availability, low price and environmentally benign character of iron mean that it is an ideal alternative to precious metals in catalysis. Recent growth in the number of iron-catalysed reactions reported reflects an increasing demand for sustainable chemistry. Only a limited number of chiral iron catalysts have been reported and these have, in general, proven less enantioselective than other transition-metal catalysts, thus limiting their appeal. Here, we report that iron complexes of spiro-bisoxazoline ligands are highly efficient catalysts for asymmetric O-H bond insertion reactions. These complexes catalyse insertions into the O-H bond of a wide variety of alcohols and even water, with exceptional enantioselectivities under mild reaction conditions. The selectivities surpass those obtained with other transition-metal catalysts. This study should inspire and encourage the use of iron instead of traditional precious metals in the development of greener catalysts for catalytic asymmetric synthesis.
An improved bouveault-blanc ester reduction with stabilized alkali metals
Bodnar, Brian S.,Vogt, Paul F.
supporting information; experimental part, p. 2598 - 2600 (2009/08/07)
Significantly improved Bouveault-Blanc conditions for ester reduction have been developed using sodium in silica gel (Na-SG), a free-flowing powder that can be easily handled in the open atmosphere. Primary alcohols were prepared in excellent yield from a variety of aliphatic esters under mild reaction conditions. The chemistry presented here is far safer than the classic Bouveault-Blanc reduction and is competitive with more modern hydride reduction methods.
