64245-20-1

Upstream product

• 925-90-6 ethylmagnesium bromide 
• 536-74-3 phenylacetylene 
• 68669-62-5 (E)-trimethyl(2-phenylbut-1-en-1-yl)silane 
• 144108-80-5 1-(1,1-dibromobut-1-en-2-yl)benzene 
• 1528-58-1 (E/Z)-3-phenyl-2-pentenoic acid 
• 2039-93-2 1-ethylstyrene 
• 93-55-0 1-phenyl-propan-1-one 

Downstream Products

• 141739-70-0 (E)-1-methoxy-2-phenyl-1-butene 
• 958633-19-7 (Z)-4,4,5,5-tetramethyl-2-(2-phenyl-1-buten-1-yl)-1,3,2-dioxaborolane 

Relevant academic research and scientific papers

Photocatalyzed E→Z Contra-thermodynamic Isomerization of Vinyl Boronates with Binaphthol

The photocatalytic contra-thermodynamic E→Z isomerization of vinyl boronates by using a binaphthol catalyst is disclosed. The reaction, based on the transient formation of a suitable chromophore with a BINOL derivative as the catalyst, allowed geometrical isomerization in good-to-excellent Z/E ratio and excellent-to-quantitative yields. The mechanism of this E→Z contra-thermodynamic isomerization was studied, and the formation of a transient chromophore species is suggested.

Geometric E→Z Isomerisation of Alkenyl Silanes by Selective Energy Transfer Catalysis: Stereodivergent Synthesis of Triarylethylenes via a Formal anti-Metallometallation

An efficient geometrical E→Z isomerisation of alkenyl silanes is disclosed via selective energy transfer using an inexpensive organic sensitiser. Characterised by operational simplicity, short reaction times (2 h), and broad substrate tolerance, the reaction displays high selectivity for trisubstituted systems (Z/E up to 95:5). In contrast to thermal activation, directionality results from deconjugation of the π-system in the Z-isomer due to A1,3-strain thereby inhibiting re-activation. The structural importance of the β-substituent logically prompted an investigation of mixed bis-nucleophiles (Si, Sn, B). These versatile linchpins also undergo facile isomerisation, thereby enabling a formal anti-metallometallation. Mechanistic interrogation, supported by a theoretical investigation, is disclosed together with application of the products to the stereospecific synthesis of biologically relevant target structures.

Contra-Thermodynamic, Photocatalytic E→Z Isomerization of Styrenyl Boron Species: Vectors to Facilitate Exploration of Two-Dimensional Chemical Space

Designing strategies to access stereodefined olefinic organoboron species is an important synthetic challenge. Despite significant advances, there is a striking paucity of routes to Z-α-substituted styrenyl organoborons. Herein, this strategic imbalance is redressed by exploiting the polarity of the C(sp2)?B bond to activate the neighboring π system, thus enabling a mild, traceless photocatalytic isomerization of readily accessible E-α-substituted styrenyl BPins to generate the corresponding Z-isomers with high fidelity. Preliminary validation of this contra-thermodynamic E→Z isomerization is demonstrated in a series of stereoretentive transformations to generate Z-configured trisubstituted alkenes, as well as in a concise synthesis of the anti-tumor agent Combretastatin A4.

A novel system for decarboxylative bromination

A simple and mild method for decarboxylative bromination of α,β-unsaturated carboxylic acids has been developed using diphosphorus tetraiodide in combination with tetraethylammonium bromide (TEAB) at room temperature. High yields of the corresponding bromoalkenes were obtained.

Stereochemistry in carbenoid formation by bromine/lithium and bromine/zinc exchange reactions of gem-dibromo compounds

Stereochemistry in generation of lithium and zincate carbenoids by bromine/metal exchange reactions of gem-dibromo compounds with BuLi and lithium triorganozincates, respectively, has been investigated. Both lithium and zincate carbenoids derived from 1,1

Reactions of 1,1-Dihaloalkenes with Triorganozincates: A Novel Method for the Preparation of Alkenylzinc Species Associated with Carbon-Carbon Bond Formation

Lithium trialkylzincates react with 1,1-dibromoalkenes 1 and 1-bromo-1-chloroalkenes 2 at -85 deg C in THF to give 1-bromoalkenes 5 and 1-chloroalkenes 7, respectively, upon hydrolysis.The intermediate (1-haloalkenyl)zincates 4 and 6 are stable at low temperature but, when allowed to warm to 0 deg C, they undergo a 1,2-alkyl migration reaction to afford alkenylzinc species 10.A variety of alkylation products 11 are obtained by the hydrolysis of 10.In the presence of (Ph3P)2Pd (5 molpercent), alkenylzinc species 10 react smoothly with organic halides (AcCl, EtOCOCl, CH2=CH(Me)Br, PhBr) to yield the corresponding coupling products 13-16.

Stereochemistry in Carbenoid Formation by Bromine/Lithium and Bromine/Zinc Exchange Reactions of 1,1-Dibromoalkenes: Higher Reactivity of the Sterically More Hindered Bromine Atom

Both lithium and zincate carbenoids (R1(R2)C=C(Br)M; M = Li and Zn(Bu)2Li) generated by the halogen/metal exchange reaction of 1,1-dibromoalkene 1 with BuLi and (Bu)3ZnLi, respectively, are configurationally stable at low temperature

Regiospecific and Stereospecific Synthesis of E- and Z-Trisubstituted Alkenes via 2,2-Disubstituted Vinylsilanes

Treatment of terminal alkynes 1 with the organocopper reagents derived from Grignard reagents, cuprous iodide, and lithium bromide (molar ratio 2:1:2) at low temperature followed by the addition of chlorotrimethylsilane gave the 2,2-disubstituted vinylsilanes 2 with complete regio- and stereospecificity (syn addition).Electrophilic substitution of 2 with ICl, Br2, and acetyl chloride gave the corresponding vinyl iodides, bromides, and α,β-unsaturated ketones 5 with retention of configuration.Epoxidation of 2 with MCPBA gave the epoxy silanes 6, which upon treatment with concentrated HX and BF3*Et2O gave the vinyl halides 7 with net inversion of configuration.If the epoxy silanes 6 were first converted to the β-hydroxy silanes 8 by Gilman's reagents, either E- or Z-trisubstituted alkenes 9 and 10 could be obtained by treatment with acid or base.Vinyl halides 7 could also be stereoselectively converted to other functionalities via the vinyllithium intermediates.