4187-60-4Relevant academic research and scientific papers
Selective Isomerization via Transient Thermodynamic Control: Dynamic Epimerization of trans to cis Diols
Macmillan, David W. C.,Oswood, Christian J.
, p. 93 - 98 (2022/01/03)
Traditional approaches to stereoselective synthesis require high levels of enantio- and diastereocontrol in every step that forms a new stereocenter. Here, we report an alternative approach, in which the stereochemistry of organic substrates is selectivel
Investigation of Electrostatic Interactions towards Controlling Silylation-Based Kinetic Resolutions
Zhang, Tian,Redden, Brandon K.,Wiskur, Sheryl L.
supporting information, p. 4827 - 4831 (2019/08/12)
Electrostatic interactions between a silylated isothiourea intermediate and an ester π system were explored by determining how variations in sterics and electronics affect the selectivity of a silylation-based kinetic resolution. Sterics on the π systems affect the selectivity factors of alkyl 2-hydroxycyclohexanecarboxylates, resulting in a strong correlation of selectivity factors to Charton values. Induction effects of electron-withdrawing substituents on phenyl esters significantly enhance selectivity supporting an edge to face π–π interaction. The linear free energy relationships that were uncovered will aid in future incorporation of intermolecular electrostatic interactions towards controlling asymmetric reactions.
Chemoenzymatic approaches to the synthesis of the (1S,2R)-isomer of benzyl 2-hydroxycyclohexanecarboxylate
Tsunekawa, Ryuji,Hanaya, Kengo,Higashibayashi, Shuhei,Shoji, Mitsuru,Sugai, Takeshi
, p. 84 - 89 (2017/12/06)
We examined ten strains of cultured whole-cell yeasts for the asymmetric reduction of commercially available ethyl 2-oxocyclohexanecarboxylate, and found that the (1S,2S)-stereoisomer of ethyl 2-hydroxycyclohexanecarboxylate was the major stereoisomer produced by Williopsis californica JCM 3600. The ethyl group of the ester was then substituted with a benzyl group with low volatility and increased hydrophobicity to facilitate the isolation of the expected product. Incubation with W. californica furnished benzyl (1S,2S)-2-hydroxycyclohexanecarboxylate (>99.9% ee) in 51.0% yield together with its (1R,2S)-isomer (>99.9% ee) in 35.4% yield. Upon treatment of the same substrate bearing the benzyl ester with a screening kit of purified overexpressed carbonyl reductases (Daicel Chiralscreen OH), two enzymes (E031, E078) furnished the (1R,2S)-isomer as the major product. With another enzyme (E007), the (1S,2R)-isomer was obtained, but its ee was very low (25.6%). The highly enantiomerically enriched (1S,2S)-isomer obtained by W. californica was transformed to the (1S,2R)-isomer (>99.9% ee), whose availability until now has been low, in 43.3% yield over two steps involving tosylation and subsequent inversive attack with tetrabutylammonium nitrite.
SN2 Reactions at Tertiary Carbon Centers in Epoxides
Zhang, Yong-Qiang,Poppel, Christina,Panfilova, Anastasia,Bohle, Fabian,Grimme, Stefan,Gans?uer, Andreas
supporting information, p. 9719 - 9722 (2017/08/08)
Described herein is a novel concept for SN2 reactions at tertiary carbon centers in epoxides without activation of the leaving group. Quantum chemical calculations show why SN2 reactions at tertiary carbon centers are proceeding in these systems. The reaction allows flexible synthesis of 1,3-diol building blocks for natural product synthesis with excellent control of the relative and absolute configurations.
Regioselective mono-deprotection of di-ferf-butylsilylene acetal derived from 1,3-diol with ammonium fluoride
Ohtawa, Masaki,Tomoda, Hiroshi,Nagamitsu, Tohru
, p. 113 - 118 (2014/02/14)
Here we report a novel and efficient method for the regioselective mono-deprotection of di-terf-butylsilylene acetals derived from 1,3-diols consisting of primary and secondary alcohols. The ammonium fluoride-mediated reactions of pyripyropene A derivative, thymidine and uridine derivatives, methyl β-D-glucofuranoside, and pyranoside derivatives each gave the corresponding primary alcohol with high regioselectivity.
Synthesis and characterization of the enantiomerically pure cis- and trans-2,4-dioxa-3-fluoro-3-phosphadecalins as inhibitors of acetylcholinesterase
Waechter, Michael,Rueedi, Peter
experimental part, p. 283 - 294 (2010/04/23)
The title compounds, the P(3)-axially- and P(3)-equatorially-substituted cis- and trans-configured 3-fluoro-2,4-dioxa-3-phosphadecalin 3-oxides (= 3-fluoro-2,4-dioxa-3-phosphabicyclo[4.4.0]decane 3-oxides) have been prepared (ee > 99%) and fully character
Platinum-triethylamine-catalyzed hydrogenation of aldehydes and cyclohexanones
Gao, Feng,Chen, Qiao-Hong,Wang, Feng-Peng
supporting information; experimental part, p. 5270 - 5273 (2009/12/24)
The first hydrogenation of aldehydes and chemoselective hydrogenation of cyclohexanones catalyzed by PtO2-Et3N are presented. An additionally attractive feature of this hydrogenation is being applicable to the complicated molecules. Three equivalent of triethylamine and 0.05 equiv of PtO2 in 95% ethanol are found to be the optimal condition.
1,2-Disubstituted cyclohexane carbocyclic analogues of nucleosides
Vina,Santana,Uriarte
, p. 1363 - 1365 (2007/10/03)
Several compounds of a new series of cyclohexane-based 1,2-disubstituted carbonucleoside analogues, were synthesized. The adenine and uridine derivatives, were prepared by construction of the heterocyclic base on the primary amino group of 2-aminocyclohexylmethanol, and the thymine derivative by condensation of 2-hydroxycyclohexylmethanol with thymine using the Mitsunobu reaction.
Tethered α-boryl radical cyclizations of haloalkyl boronates
Batey, Robert A.,Smil, David V.
, p. 9183 - 9187 (2007/10/03)
Boroalkyl radicals readily cyclize onto alkenyl and alkynyl traps tethered via a C-B-O linkage. Oxidative cleavage of the C-B bond of the temporary connection following cyclization affords 1,3-diols in good yields.
Catalytic Cyclization/Silylation of Dienes Containing 1,1-Disubstituted Olefins Using Organolanthanide and Group 3 Organometallic Complexes
Molander, Gary A.,Dowdy, Eric D.,Schumann, Herbert
, p. 3386 - 3396 (2007/10/03)
The catalytic cyclization/silylation reaction of hindered dienes has been investigated using the relatively unhindered complexes Me2Si(C5H3SiMe3) 2YCH(TMS)2 and [CpTMS2LnMe]2 (Ln = Y, Lu). A wide variety of dienes and trienes bearing a number of functional groups were cychzed, affording silanes containing quaternary centers in a diastereoselective fashion and in good yield. The products can be oxidized using one of several different protocols, yielding alcohols for further functionalization.
