- Enantioselective Allylation of Indoles: A Surprising Diastereoselectivity
-
Herein we show a novel approach toward the allylation of indoles. Thereby, we explore a class of bench-stable allylboronates and fine-tune their reactivity. The allylations of different substituted indoles proceed with negligible diastereo- and excellent enantioselectivities. This surprising selectivity (up to 99:1 er, up to ≈60:40 dr) is rationalized by DFT calculations.
- Brauns, Marcus,Breugst, Martin,Mantel, Marvin,Pietruszka, J?rg,Schmauck, Julie,Ullrich, Patrick
-
-
Read Online
- Host behaviour of related compounds, TETROL and DMT, in the presence of two different classes of aromatic guest compounds
-
The host potential of two closely-related compounds, TETROL [(+)-(2R,3R)-1,1–4,4-tetraphenylbutane-1,2,3,4-tetraol] and DMT [(?)-(2R,3R)-2,3-dimethoxy-1,1,4,4-tetraphenylbutane-1,4-diol], were compared when recrystallized from two different classes of guests, namely toluene, ethylbenzene, cumene and aniline, N-methylaniline, N,N-dimethylaniline. TETROL formed complexes with only aniline and N-methylaniline (host:guest ratios, 2:3 and 2:4), while DMT included all six guests with a consistent ratio (2:1). Aniline competition experiments showed that TETROL preferred aniline (67%), followed by N-methyl- (29%) and N,N-dimethyl- (4%) aniline; surprisingly, this order was exactly reversed for DMT [N,N-dimethylaniline (62%) > N-methylaniline (32%) > aniline (6%)]. Crystal diffraction analyses revealed that TETROL formed stabilizing hydrogen bonds with guests, behaving as both donor and, for the first time, acceptor (in 2TETROL?4N-methylaniline). DMT did not form bonds of this type with any guests. Furthermore, the host packing was isostructural for all DMT complexes but was guest-dependent for TETROL. Thermal analyses showed that complex stabilities correlated precisely with the host preferences.
- Barton, Benita,de Jager, Lize,Dorfling, Sasha-Lee,Hosten, Eric C.,McCleland, Cedric W.,Pohl, Pieter L.
-
-
Read Online
- The intramolecular S = O···H-O hydrogen bond in a chiral cyclic sulfite ester: How it affects the reaction behavior and spectral properties
-
The intramolecular S = O···H?O hydrogen bond in a chiral cyclic sulfite ester, which affects the reaction behavior and spectral properties considerably, was studied.
- Hu, Xiaoyun,Chen, Dongzhi,Lan, Jirong,Shan, Zixing
-
-
Read Online
- A novel, high-yielding approach to a chiral inducer: (2R,3R)-1,4-dimethoxy- 1,1,4,4-tetraphenylbutane-2,3-diol
-
A new method for preparing (2R,3R)-1,4-dimethoxy-1,1,4,4-tetraphenylbutane- 2,3-diol in high yield based on selective 2,3-spiroboration of (2R,3R)-1,1,4,4-tetraphenylbutanetetraol has been developed. It avoids traditional oxidation and reduction steps, and provides a simplified, more straightforward, and high-yielding synthesis of the title compound.
- Hu, Xiaoyun,Shan, Zixing,Song, Shaojun
-
-
Read Online
- DMT [(?)-(2R,3R)-2,3-dimethoxy-1,1,4,4-tetraphenylbutane-1,4-diol], a highly efficient host compound for nitroaromatic guests: selectivity, X-ray and thermal analyses
-
In this work, we reveal that the compound (?)-(2R,3R)-2,3-dimethoxy-1,1,4,4-tetraphenylbutane-1,4-diol (DMT) is a highly efficient host material for nitroaromatics o-nitrotoluene (o-NT), m-nitrotoluene (m-NT), p-nitrotoluene (p-NT) and nitrobenzene (NB). Each of these guests was included with a 2:1 host:guest ratio. The host displayed selectivity for p-NT and NB when these guests were mixed in equimolar proportions with any one of the other guest solvents, and the host recrystallized from this binary mixture. A selectivity order for the host in these conditions was thus noted to be NB ≈ p-NT > o-NT > m-NT. Furthermore, guests were also mixed in non-equimolar proportions and the host behaviour analysed, the results of which were in accordance with observations from the equimolar studies. Additionally, an equimolar quaternary experiment of all four guests provided a somewhat adjusted host selectivity order [p-NT (39.9%) > NB (30.2%) > m-NT (17.1%) > o-NT (12.8%)]. Single crystal diffraction analyses of all four complexes showed the crystals to share the same host packing, and comparable host–guest interactions were observed in each. However, thermal analyses, both DSC and TG, showed that the preferred guests p-NT and NB formed complexes with increased relative thermal stabilities, and this observation correlated with the selective behaviour of the host in competition experiments.
- Barton, Benita,Hosten, Eric C.,Pohl, Pieter L.
-
-
Read Online
- Discrimination between o-xylene, m-xylene, p-xylene and ethylbenzene by host compound (R,R)-(–)-2,3-dimethoxy-1,1,4,4-tetraphenylbutane-1,4-diol
-
The title host compound (R,R)-(?)-2,3-dimethoxy-1,1,4,4-tetraphenylbutane-1,4-diol 3, when recrystallized from each of the isomeric xylenes and ethylbenzene, formed a 2:1 host:guest complex in each instance. Competition experiments where 3 was recrystallized from various equimolar binary, ternary and quaternary mixtures of these guests indicated that 3 displayed a consistent preference for para-xylene whenever it was present: when 3 was recrystallized from equimolar binary and ternary mixtures of the xylenes, the selectivity order was para-xylene???ortho-xylene?>?meta-xylene while recrystallization from equimolar binary and quaternary mixtures of the xylenes and ethylbenzene showed a selectivity order of para-xylene?>?ethylbenzene?>?ortho-xylene?>?meta-xylene. Thermal experiments showed that the higher the relative thermal stability of the complex, the higher was the host's preference for it. However, no dominant differences in the strength or nature of intermolecular host-guest interactions could be singled out from crystal data to explain these observations.
- Barton, Benita,Hosten, Eric C.,Pohl, Pieter L.
-
-
Read Online
- Enantioselective Allylation of Cyclic and In Situ Formed N-Unsubstituted Imines with Tetraol-Protected Allylboronates
-
Tetraol-protected α-chiral allylboronates are utilized in diastereo- and enantioselective transformations of cyclic imines (up to 98 %, d.r. 97 : 3, e.r. 99 : 1). An application to in situ formed N-unsubstituted imines gives in a consecutive one-pot sequence selective access to all four stereoisomers of the homoallylamine within minutes (up to 88 %, d.r. 81 : 19, e.r. 99 : 1). These results underline the usability, tuneability and stability of tetraol-based allylboronates.
- Ullrich, Patrick,Schlamkow, Max A.,Choi, Ching-Yi,Kerkenpa?, Hannah,Hen?en, Birgit,Pietruszka, J?rg
-
supporting information
p. 6254 - 6257
(2021/11/03)
-
- Stereoselective Biginelli-like reaction catalyzed by a chiral phosphoric acid bearing two hydroxy groups
-
To develop new efficient stereoselective catalysts for Biginelli-like reactions, a chiral phosphoric acid bearing two hydroxy groups derived from L-tartaric acid was successfully synthesized via highly regioselective transformations of enantiopure 1,1,4,4
- Hu, Xiaoyun,Guo, Jianxin,Wang, Cui,Zhang, Rui,Borovkov, Victor
-
p. 1875 - 1880
(2020/09/03)
-
- Chiral bicyclo[4.4.0]diboronic acid, preparation method and application thereof
-
Belonging to the chemical field of preparation of chiral compounds, the invention in particular relates to a chiral bicyclo[4.4.0]diboronic acid, a preparation method and application thereof. The method starts from chiral 1, 1, 4, 4-tetraarylbutantetraol,
- -
-
Paragraph 0027; 0028
(2019/05/16)
-
- Host compounds (+)-(2R,3R)-1,1,4,4-tetraphenylbutane-1,2,3,4-tetraol (TETROL) and (2R,3R)-(?)-2,3-dimethoxy-1,1,4,4-tetraphenylbutane-1,4-diol (DMT) with guests o-, m- and p- toluidine: A comparative investigation
-
In this work, we have compared the host abilities of closely related compounds (+)-(2R,3R)-1,1,4,4-tetraphenylbutane-1,2,3,4-tetraol (TETROL) and (2R,3R)-(?)-2,3-dimethoxy-1,1,4,4-tetraphenylbutane-1,4-diol (DMT) when these were recrystallized from single and mixed toluidine guests. Significant differences in host behaviour and selectivities were revealed and these were explained by means of single crystal diffraction experiments. Thermal analyses were used to determine the relative complex stabilities, and these data correlated exactly with the host selectivity orders for both TETROL and DMT.
- Barton, Benita,Dorfling, Sasha-Lee,Hosten, Eric C.,Pohl, Pieter L.
-
p. 2754 - 2761
(2018/04/30)
-
- Highly Enantioselective Allylation of Ketones: An Efficient Approach to All Stereoisomers of Tertiary Homoallylic Alcohols
-
An optimized protecting group for allylboronates allowed the use of ketones in order to synthesize all isomers of quaternary homoallylic alcohols with high enantioselectivities. All symmetric isomers of the allylboronate were prepared in high yields and diastereoselectivities using Sn2′ reactions. The improved reactivity of the novel protecting group was verified by following the reaction kinetics with 1H NMR spectroscopy. Mechanistic studies using DFT calculations were conducted to investigate the new findings. Thus, the stereochemical outcome and enhanced reactivity can be rationalized.
- Brauns, Marcus,Mantel, Marvin,Schmauck, Julie,Guder, Marian,Breugst, Martin,Pietruszka, J?rg
-
supporting information
p. 12136 - 12140
(2017/09/13)
-
- Synthesis of a novel sterically hindered chiral cyclic phosphoric acid derived from L-tartaric acid and application to the asymmetric catalytic Biginelli reaction
-
A novel sterically hindered chiral cyclic phosphoric acid derived from L-tartaric acid was designed and synthesized based on highly regioselective cyclosulfitation of chiral 1,1,4,4-tetraphenylbutanetetraol. The asymmetric Biginelli reaction catalyzed by
- Hu, Xiaoyun,Zhang, Rui,Xie, Jinsheng,Zhou, Zhongqiang,Shan, Zixing
-
-
- Enantioselective Catalysts for the Synthesis of α-Substituted Allylboronates - An Accelerated Approach towards Isomerically Pure Homoallylic Alcohols
-
The use of a convenient protecting group for boronates allows a selective, catalyzed SN2′ reaction to generate allylboronates which are applied for the synthesis of enantiomerically pure homoallylic alcohols. Depending on the configuration of both catalyst and the protecting group any of the four possible stereoisomers can be formed. The rationale behind the selective addition is supported by density functional theory calculations.
- Brauns, Marcus,Muller, Frdric,Gülden, Daniel,B?se, Dietrich,Frey, Wolfgang,Breugst, Martin,Pietruszka, J?rg
-
supporting information
p. 1548 - 1552
(2016/02/12)
-
- Chiral 5,5,10,10-tetraaryl-bicyclo[4.4.0]-3,8-bisphosphate and preparation method and application thereof
-
The invention discloses chiral 5,5,10,10-tetraaryl-bicyclo[4.4.0]-3,8-bisphosphate, a preparation method of the 5,5,10,10-tetraaryl-bicyclo[4.4.0]-3,8-bisphosphate and application of the 5,5,10,10-tetraaryl-bicyclo[4.4.0]-3,8-bisphosphate. The structural formula of the chiral compound is as follows: shown in the description. The preparation method comprises the following steps of reacting optically pure tartaric ester with a Grignard reagent to obtain chiral 1,1,4,4-tetraaryl butantetraol; under the presence of organic alkali, performing high regioselective 1,3-cylcophosphorylation reaction on the chiral 1,1,4,4-tetraaryl butantetraol and phosphorus oxychloride at a temperature of 0 to 36 DEG C so as to obtain the chiral 5,5,10,10-tetraaryl-dicyclo[4.4.0]-3,8-diphosphonic acid. The chiral 5,5,10,10-tetraaryl-bicyclo[4.4.0]-3,8-bisphosphate has the advantage of excellent chiral induction capability, and can be used for catalyzing asymmetric synthesis. The method has the advantages of easiness in material obtainment, simplicity in technological process, simplicity in operation, good reaction selectivity and high product yield.
- -
-
Paragraph 0026
(2017/01/17)
-
- A straightforward and practical approach to chiral inducer: (2R,3R)-1,4-dimethoxy-1,1,4,4-tetraphenylbutane-2,3-diol
-
A straightforward and practical access to chiral inducer (2R,3R)-1,4- dimethoxyl-1,1,4,4-tetraphenyl-2,3-diol has been developed. It is based on highly regioselective 2,3-cyclosulfitation of (2R,3R)-1,1,4,4-tetraphenyl-butanetetraol, in which selective pr
- Xie, Jin-Sheng,Hu, Xiao-Yun,Shan, Zi-Xing,Zhou, Zhong-Qiang
-
p. 995 - 998
(2015/06/23)
-
- A computational, X-ray crystallographic and thermal stability analysis of TETROL and its pyridine and methylpyridine inclusion complexes
-
The identification and application of (+)-(2R,3R)-1,1,4,4- tetraphenylbutane-1,2,3,4-tetrol (TETROL) as an efficient and selective host compound is described. Computational and single crystal X-ray diffraction analyses revealed that the butane backbone of TETROL adopts a relatively rigid anti-conformation, with the hydroxy groups oriented syn and connected through a cyclic, homodromic arrangement of their O-H bonds. This structure is stabilised through a pair of 1,3-hydrogen bonding interactions. TETROL forms inclusion complexes with pyridine and 3- and 4-methylpyridine, and does so selectively from mixtures of the pyridines. X-ray diffraction (single crystal and powder) and thermal analyses of the inclusion compounds are described.
- Barton, Benita,Caira, Mino R.,Hosten, Eric C.,McCleland, Cedric W.
-
p. 8713 - 8723
(2013/09/23)
-
- A convenient approach to C2-chiral 1,1,4,4-tetrasubstituted butanetetraols: Direct alkylation or arylation of enantiomerically pure diethyl tartrates
-
C2-Chiral 1,1,4,4-tetraaryl- or 1,1,4,4-tetraalkyl-substituted butanetetraols have been conveniently synthesized via arylation or alkylation of unprotected diethyl (2R,3R)- and (2S,3S)-tartrates with Grignard reagent. The chiral 1,1,4,4-tetrasubstituted butanetetraols were characterized by IR, 1 H- and 13C-NMR, as well as LC/MS.
- Shan, Zixing,Hu, Xiaoyun,Zhou, Yan,Peng, Xitian,Li, Zhen
-
experimental part
p. 497 - 503
(2010/06/14)
-
- Selective 1,3-cycloboronation of enantiopure 1,1,4,4-tetrasubstituted butanetetraols: versatile preparation, structural characterization, and properties of chiral cyclic boron-containing bifunctional Lewis acids
-
The selective cycloboronation of enantiopure 1,1,4,4-tetrasubstituted butanetetraols was investigated, and a general preparation of chiral cyclic boron-containing bifunctional Lewis acids was discovered. Compounds (2R,3R)- or (2S,3S)-1,1,4,4-tetrasubstituted butanetetraols were reacted with ArB(OH)2 at reflux in toluene, or THF, or under solvent-free condition to furnish tricoordinated, chiral bicyclo[4.4.0]diboronic esters in high yield via selective 1,3-cycloboronation. Structural characterization and properties of the novel chiral boron compounds are also reported.
- Shan, Zixing,Hu, Xiaoyun,Zhou, Yan,Peng, Xitian,Yi, Jing
-
experimental part
p. 1445 - 1450
(2009/12/01)
-
- Convenient access to sterically hindered C2 chiral 2,2,5,5-tetraphenyltetrahydrofuran-3,4-diols: intramolecular selective 1,4-cyclocondensation of (2R,3R)- and (2S,3S)-1,1,4,4-tetraphenylbutanetetraols
-
Sterically hindered C2 chiral (3R,4R)- and (3S,4S)-2,2,5,5-tetraphenyltetrahydrofuran-3,4-diols have been conveniently prepared in a very high yield via heterogeneous intramolecular selective 1,4-cyclocondensation of (2R,3R)- and (2S,3S)-1,1,4,
- Hu, Xiaoyun,Shan, Zixing,Peng, Xitian,Li, Zhen
-
experimental part
p. 2474 - 2478
(2010/03/05)
-
- A Novel Bicyclic Orthoester as a Chiral Auxiliary: Application to the Synthesis of α-Hydroxy Acids
-
Chiral α-keto orthoesters derived from tartanic acid can be reduced diastereoselectively.Hydrolysis affords optically actice α-hydroxy acids and the recovered auxiliary.
- Dube, D.,Deschenes, D.,Tweddell, J.,Gagnon, H.,Carlini, R.
-
p. 1827 - 1830
(2007/10/02)
-
- DESIGN OF A NEW CHIRAL HOST COMPOUND, TRANS-4,5-BIS(HYDROXYDIPHENYLMETHYL)-2,2-DIMETHYL-1,3-DIOXACYCLOPENTANE. AN EFFECTIVE OPTICAL RESOLUTION OF BICYCLIC ENONES THROUGH HOST-GUEST COMPLEX FORMATION
-
The title chiral host compound which was derived from tartaric acid was found to be effective for optical resolution of bicyclic enones through complex formation between them.
- Toda, Fumio,Tanaka, Koichi
-
p. 551 - 554
(2007/10/02)
-