20218-42-2

Upstream product

• 67-56-1 methanol 
• 584-02-1 2-pentanol 
• 121700-16-1 1,1-dichloro-2-phenyl-1-butene 
• 74-85-1 ethene 
• 501-65-5 diphenyl acetylene 
• 67-63-0 isopropyl alcohol 
• 96-10-6 diethylaluminium chloride 
• 557-20-0 diethylzinc 
• 252975-34-1 selenophosphoric acid Se-(1-benzoyl-1-phenylpropyl) ester O,O-diethyl ester 
• 624-31-7 4-tolyl iodide 
• 624731-39-1 (Z)-2-(1,2-diphenylbut-1-en-1-yl)-4,4,5,5-tetramethyl-1,3,2-dioxaborolane 
• 51934-41-9 4-iodobenzoic acid ethyl ester 
• 624731-31-3 E-(Et)(C₆H₅)CC(C₆H₅)(SiMe₂C₅H₄N) 
• 925-90-6 ethylmagnesium bromide 

Downstream Products

• 93-55-0 1-phenyl-propan-1-one 
• 65-85-0 benzoic acid 

Relevant academic research and scientific papers

Preparation and reactions of monocyclic bis(cyclopentadienyl)titanacyclopentenes and -pentadienes

A combination of Cp2TiCl2-2EtMgBr was found to be very effective for the formation of monocyclic titanacyclopentenes in excellent yields. On the other hand, a combination of Cp2TiCl2-2n-BuLi was used for intermolecular coupling of two alkynes to form titanacyclopentadienes in good to excellent yields. A reaction temperature range from -10 to -30°C was critical for the success of the combinations. Reactions of these in situ-prepared titanacycles show interesting similarities to or differences from their zirconacycle analogs.

Stereoconvergent and -divergent synthesis of tetrasubstituted alkenes by nickel-catalyzed cross-couplings

We report the development of a method to diastereoselectively access tetrasubstituted alkenes via nickel-catalyzed Suzuki-Miyaura cross-couplings of enol tosylates and boronic acid esters. Either diastereomeric product was selectively accessed from a mixture of enol tosylate starting material diastereomers in a convergent reaction by judicious choice of the ligand and reaction conditions. A similar protocol also enabled a divergent synthesis of each product isomer from diastereomerically pure enol tosylates. Notably, high-throughput optimization of the monophosphine ligands was guided by chemical space analysis of the kraken library to ensure a diverse selection of ligands was examined. Stereoelectronic analysis of the results provided insight into the requirements for reactive and selective ligands in this transformation. The synthetic utility of the optimized catalytic system was then probed in the stereoselective synthesis of various tetrasubstituted alkenes, with yields up to 94% and diastereomeric ratios up to 99:1 Z/E and 93:7 E/Z observed. Moreover, a detailed computational analysis and experimental mechanistic studies provided key insights into the nature of the underlying isomerization process impacting selectivity in the cross-coupling.

Regioselective Synthesis of α-Functional Stilbenes via Precise Control of Rapid cis- trans Isomerization in Flow

The rapid cis-trans isomerization of α-anionic stilbene was regioselectively controlled by using flow microreactors, and its reaction with various electrophiles was conducted. The reaction time was precisely controlled within milliseconds to seconds at -50 °C to selectively give the cis- or trans-isomer in high yields. This synthetic method in flow was well-applied to synthesize precursors of commercial drug compound, (E)- and (Z)-tamoxifen with high regioselectivity and productivity.

Trans-stilbene as a starting material for the synthesis of tamoxifen based on palladium-catalyzed cross-coupling reactions

(Z)-Tamoxifen was synthesized from a simple olefin (trans-stilbene) in 5 steps and 40% overall yield (Z/E = 74:26). The phenyl substituted group (4-Me2NCH2CH2OC6H4) was attached by a bromination-dehydrobromination-Suzuki reaction sequence. Subsequently, the ethyl group was attached to the triarylated olefin by a bromination-Negishi reaction sequence. Both the Suzuki and Negishi cross-coupling processes are stereospecific, and the stereo-selectivity depends only on the bromination-dehydrobromination reactions. (Z)-Tamoxifen was also obtained from trans-stilbene in only 3 steps by using Heck reaction-bromination- Negishi reaction sequence in 57% overall yield (Z/E = 65:35). Georg Thieme Verlag Stuttgart.

New method for cycloalumination of disubstituted acetylenes with 1,2-dichloroethane

A new procedure has been developed for the synthesis of 2,3-dialkyl(phenyl)aluminacyclopent-2-enes by Cp2TiCl 2-catalyzed cycloalumination of disubstituted acetylenes with EtAlCl2 in the presence of ethylene generated in situ from 1,2-dichloroethane and activated magnesium.

Yttrium-mediated conversion of vinyl grignard reagent to a 1,2-dimetalated ethane and its synthetic application

A new 1,2-dimetalated ethane was generated from a vinyl Grignard reagent in the presence of yttrium(III) chloride, sodium cyclopentadienide, and diisobutylaluminum hydride (Dibal). This reagent enables the regio- and stereoselective (metaloethyl)metalation of acetylenes to produce ethylated alkenes after hydrolysis. In addition to simple hydrolysis, further carbon-carbon bond formation or functionalization at the metaloethyl group is possible, demonstrating that the yttrium-based 1,2-dimetalated ethane works as a conjunctive reagent. In addition, the reactive dicarbanionic character of this reagent effects one-pot synthesis of cyclopronanols from esters via consecutive double carbonyl addition. Copyright

Synthesis of tri- and tetrasubstituted olefins by palladium cross-coupling reaction

Tri- and tetrasubstituted olefins were obtained in high yields and regioselectivities using stilbene as starting material. First, stilbene was converted into (E)-bromostilbene by a bromination-dehydrobromination sequence. Then, (E)-bromostilbene was coupled with arylboronic acids at room temperature and low loading of Pd catalyst precursor (0.5-0.05 mol%) to afford selectively (E)-1-aryl-1,2-phenylethylenes in high yields (87-98%). Bromination of triphenylethylene afforded directly the bromotriphenylethylene that also underwent coupling reactions with arylboronic acids under mild conditions to afford tetrarylethylene (88-90% yield). Under the same conditions attempted Suzuki cross-coupling reactions of (E)-bromostilbene or 1,1,2-triphenylethene with alkylboronic acids were unsuccessful. However, the alkyl group could be introduced under mild conditions and high yields by using a Pd-catalyzed Negishi coupling protocol. Georg Thieme Verlag Stuttgart.

The reactivity of epoxides with lithium 2,2,6,6-tetramethylpiperidide in combination with organolithiums or grignard reagents

(Chemical Equation Presented) The scope and limitations of lithium 2,2,6,6-tetramethylpiperidide (LTMP)-modified reductive alkylation of epoxides is detailed. A variety of organolithiums are added to terminal and 2,2-disubstituted epoxides in the presence of LTMP to generate alkenes in a completely regio- and highly stereoselective manner. Arylated alkenes, dienes, allylsilanes, and enynes are accessed using this procedure. The methodology is applied in the synthesis of the roller leaf moth pheromone, (3E,5Z)-dodecadienyl acetate. The corresponding reaction without LTMP has also been examined, and a study using deuterated epoxides provides insight into the mechanism. In the presence of LTMP, Grignard reagents are also shown to produce E-alkenes directly from epoxides.

A novel reaction of titanacyclopentenes and aldehydes with or without Lewis acids

Oxatitanacyclopentenes were prepared in high yields from the reaction of aldehydes with titanacyclopenetens via substitution of ethylene. No insertion product was obtained in this reaction. The combination of alkynes and aldehydes played an important role in the successive formation of oxatitanacyclopentenes. Some oxatitanacyclopentenes are very stable and can be purified using column chromatography. The cooperation between Ti and LA led to very different results from that between Zr and LA.

Carbolithiation of diphenylacetylene as a stereoselective route to (Z)-tamoxifen and related tetrasubstituted olefins

(Chemical Equation Presented) Carbolithiation of diphenylacetylene can be exploited to generate (E)-1-lithio-1,2-diphenylalkyl-1-enes which can be reacted in situ with triisopropylborate to stereoselectively provide (E)-1,2-diphenyl-1-alkylene boronic acids. These tetrasubstituted vinylboronic acids served as versatile intermediates for the generation of tetrasubstituted olefins with retention of stereochemistry. The application of this method for the stereoselective synthesis of (Z)-tamoxifen and related analogues is described.