31593-52-9Relevant academic research and scientific papers
N-heterocyclic carbene-catalyzed asymmetric synthesis of cyclopentenones
Chen, Zhizhou,Kong, Xiangwen,Niu, Shengtong,Yang, Shuang,Liu, Jinggong,Chen, Bolai,Luo, Benlong,Zhou, Changyu,Ding, Chenglin,Fang, Xinqiang
supporting information, p. 3403 - 3408 (2021/05/10)
N-Heterocyclic carbene-catalyzed asymmetric construction of cyclopentenones using enals and α-diketones is achieved, furnishing a series of highly functionalized cyclopentenones in a highly diastereo- and enantioselective manner. The protocol tolerates su
Enantioselective 1,2-Anionotropic Rearrangement of Acylsilane through a Bisguanidinium Silicate Ion Pair
Cao, Weidi,Tan, Davin,Lee, Richmond,Tan, Choon-Hong
supporting information, p. 1952 - 1955 (2018/02/17)
Highly enantioselective bisguanidinium-catalyzed tandem rearrangements of acylsilanes are reported. The acylsilanes were activated via an addition of fluoride on the silicon to form a penta-coordinate anionic silicate intermediate. The silicate then underwent alkyl or aryl group migration from the silicon atom to the neighboring carbonyl carbon atom (1,2-anionotropic rearrangement), followed by [1,2]-Brook rearrangement to provide the secondary alcohols in high yields with excellent enantioselectivities (up to 95% ee). The isolation of an α-silylcarbinol intermediate as well as DFT calculations revealed that the 1,2-anionotropic rearrangement occurred via a bisguanidinium silicate ion pair, which is the stereodetermining step. The chiral center formed is then retained without inversion through the subsequent [1,2]-Brook rearrangement. Crotyl acylsilanes were smoothly transformed into homoallylic linear crotyl alcohols with retention of E/Z geometry, and no branched alcohols were detected. This clearly suggested that the 1,2-anionotropic rearrangement occurred through a three-membered instead of a five-membered transition state.
Pot-economy autooxidative condensation of 2-Aryl-2-lithio-1,3-dithianes
Vale, Joao R.,Rimpil?inen, Tatu,Siev?nen, Elina,Rissanen, Kari,Afonso, Carlos A. M.,Candeias, Nuno R.
, p. 1948 - 1958 (2018/02/23)
The autoxidative condensation of 2-aryl-2-lithio-1,3-dithianes is here reported. Treatment of 2-aryl-1,3-dithianes with n-BuLi in the absence of any electrophile leads to condensation of three molecules of 1,3-dithianes and formation of highly functionalized α-thioether ketones orthothioesters in 51-89% yields upon air exposure. The method was further expanded to benzaldehyde dithioacetals, affording corresponding orthothioesters and α-thioether ketones in 48-97% yields. The experimental results combined with density functional theory studies support a mechanism triggered by the autoxidation of 2-aryl-2-lithio-1,3-dithianes to yield a highly reactive thioester that undergoes condensation with two other molecules of 2-aryl-2-lithio-1,3-dithiane.
Intermolecular Schmidt reaction of alkyl azides with acyl silanes
Yu, Chun-Jiao,Li, Rui,Gu, Peiming
supporting information, p. 3568 - 3570 (2016/07/18)
The first intermolecular Schmidt reaction of alkyl azides with acyl silanes has been designed and realized, producing a range of amides with absolute site selectivity in good to excellent yields. The mechanism of the conversion has been proposed, and the reaction exhibits scope of substrates.
Synthesis of disubstituted dithioethers: Tert -butoxide promoted elimination/ring opening of 1,3-dithianes followed by palladium-catalyzed C-S bond formation
Abidi, Nissa,Schmink, Jason R.
, p. 4123 - 4131 (2015/05/05)
We report the tandem base-promoted elimination/ring-opening of 2-benzyl-1,3-dithianes with subsequent cross coupling of the pendent thiol with a range of aryl bromides. A simple Pd(OAc)2/Xantphos catalyst system affects this new reaction and is
Calcium-catalyzed bis-hydrothiolation of unactivated alkynes providing dithioacetals
Hut'Ka, Martin,Tsubogo, Tetsu,Kobayashi, Shu
supporting information, p. 5626 - 5629 (2015/02/19)
Bis-hydrothiolation of alkynes providing anti-Markovnikov dithioacetals is reported. Lewis-acidic Ca(OSO2C4F9)2 (Ca(ONf)2) was synthesized for the first time and was shown to be an excellent catalyst
Solid-supported odorless reagents for the dithioacetalization of aldehydes and ketones
Jung,Gr?ssle,Lütjohann,Br?se
supporting information, p. 1036 - 1039 (2016/10/17)
A solid supported, odorless reagent for the dithioacetalization of aldehydes and ketones has been developed. The new reagent provides the dimercaptoalkane equivalent in combination with stoichiometric amounts of immobilized acid and enables the formation of dithianes and dithiolanes from aldehydes without any additives in good to very good yields with high purities. The reaction is chemoselective for aldehydes, but ketones can be reacted to the corresponding dithioketals if an additional Lewis acid such as BF3is added.
Organocatalytic asymmetric Michael reaction with acylsilane donors
Wu, Lei,Li, Guangxun,Fu, Qingquan,Yu, Luoting,Tang, Zhuo
supporting information, p. 443 - 447 (2013/02/23)
We have developed an organocatalytic asymmetric Michael reaction of acylsilane through the selection of acylsilane substrates and organocatalysts, thus creating a rare example of acylsilane α-alkylation with a chiral guanidine catalyst, which afforded pro
Palladium-catalyzed fluoride-free cross-coupling of intramolecularly activated alkenylsilanes and alkenylgermanes: Synthesis of tamoxifen as a synthetic application
Matsumoto, Kenji,Shindo, Mitsuru
supporting information; experimental part, p. 642 - 650 (2012/05/04)
We have demonstrated that intramolecular hypercoordination of a carboxylic acid is a powerful activation strategy for the palladium-catalyzed cross-coupling reaction of trialkyl(vinyl)silanes and trialkyl(vinyl)germanes under fluoride-free conditions. Z-β-Trialkylsilyl- and Z-β- trialkylgermylacrylic acids, synthesized stereoselectively by olefination with ynolates, are highly stable and useful reagents for cross-coupling with a variety of aryl iodides to provide tetrasubstituted olefins possessing different carbon substituents in a stereocontrolled and diversity-oriented manner. An application to a stereoselective synthesis of (Z)-tamoxifen is also reported. Copyright
Regio- and stereoselective copper-catalyzed addition of aromatic and aliphatic thiols to terminal and internal nonactivated alkynes
Trostyanskaya, Inna G.,Beletskaya, Irina P.
, p. 535 - 540 (2012/04/10)
The CuI-catalyzed regio- and stereoselective hydrothio-lation of terminal and internal alkynes affords (Z) - alkenylsulfides. The following isomerization of the Z-isomers into E-isomers catalyzed by CuI is described. Georg Thieme Verlag Stuttgart · New Yo
