865999-25-3Relevant articles and documents
Stepwise Suzuki?Miyaura Cross-Coupling of Triborylalkenes Derived from Alkynyl?B(dan)s: Regioselective and Flexible Synthesis of Tetrasubstituted Alkenes
Tani, Tomohiro,Takahashi, Naomi,Sawatsugawa, Yuuki,Osano, Mana,Tsuchimoto, Teruhisa
, p. 2427 - 2442 (2021)
Alkenes with three boryl groups of differing reactivities were synthesized and subsequently cross-coupled regioselectively with aryl halides in a stepwise manner to afford tetrasubstituted alkenes. The key triborylalkene is derived from the platinum-catalyzed diboration of alkynyl?B(dan)s with B2(pin)2. Due to excellent regioselectivity and reaction efficiency of each step starting with alkynyl?B(dan)s, tetrasubstituted alkenes with desired carbon frameworks at desired positions can be prepared in high yields. For example, an alkene with four distinct aryl groups, p-MeOC6H4, p-CF3C6H4, p-MeC6H4, and p-NCC6H4, was obtained in 71% overall yield via six steps, starting with the dehydrogenative borylation of p-MeC6H4C≡CH with HB(dan). Moreover, a variety of tetrasubstituted alkenes, including regio- and stereoisomers of the above tetraarylalkene, AIE-active TPTPE and derivatives thereof, and (Z)-tamoxifen, a well-known breast cancer drug, were accessed via the developed strategy. (Figure presented.).
Stereoselective Synthesis of Trisubstituted Vinylboronates from Ketone Enolates Triggered by 1,3-Metalate Rearrangement of Lithium Enolates
Hu, Yue,Sun, Wei,Zhang, Tao,Xu, Nuo,Xu, Jianeng,Lan, Yu,Liu, Chao
supporting information, p. 15813 - 15818 (2019/10/28)
An unprecedented stereoselective synthesis of trisubstituted vinylboronates is reported to proceed by direct borylation of lithium ketone enolates under transition-metal-free conditions. The stereospecific C?O borylation of lithium enolates was triggered by a carbonyl-induced 1,3-metalate rearrangement via a C-bound boron enolate. DFT calculations and control experiments revealed that the stereoselectivity is controlled by sterics. A variety of stereospecific trisubstituted vinylboronates, together with several tetrasubstituted vinylboronates, were conveniently synthesized with the newly developed methodology. Based on the transformation of stereospecific vinylboronate, a single isomer of Dienestrol was efficiently obtained.
Diborative Reduction of Alkynes to 1,2-Diboryl-1,2-Dimetalloalkanes: Its Application for the Synthesis of Diverse 1,2-Bis(boronate)s
Takahashi, Fumiya,Nogi, Keisuke,Sasamori, Takahiro,Yorimitsu, Hideki
, p. 4739 - 4744 (2019/06/27)
Reduction of alkynes with alkali metals in the presence of B2pin2 results in diboration of alkynes. Distinct from conventional dissolving metal hydrogenations, two carbon-boron bonds and also two carbon-alkali metal bonds can be constructed in one operation to form 1,2-diboryl-1,2-dimetalloalkanes. The 1,2-diboryl-1,2-dimetalloalkanes generated are readily convertible to a wide range of vicinal bis(boronate)s. In particular, oxidation of the 1,2-dianionic species provides (E)-1,2-diborylalkenes, unique anti-selective diboration of alkynes being thus executed.
Opportune gem-Silylborylation of Carbonyl Compounds: A Modular and Stereocontrolled Entry to Tetrasubstituted Olefins
La Cascia, Enrico,Cuenca, Ana B.,Fernández, Elena
supporting information, p. 18737 - 18741 (2016/12/26)
An easy access to highly versatile gem-silylboronate synthons is achieved by means of a new olefination reagent, HC(Bpin)2(SiMe3). Subsequent silicon or boron-based selective functionalization allows for the modular and stereocontrolled synthesis of all-carbon tetrasubstituted alkenes. A particular attraction of this approach is the iododesilylation reaction, which becomes a pivotal tool for C?Si functionalization.
Iridium-catalyzed diborylation of benzylic C-H bonds directed by a hydrosilyl group: Synthesis of 1,1-benzyldiboronate esters
Cho, Seung Hwan,Hartwig, John F.
, p. 694 - 698 (2014/01/17)
We describe a regioselective diborylation of primary benzylic C-H bonds catalyzed by [Ir(COD)OMe]2 and 4,4′-di-tert-butyl-2,2′- bipyridine (dtbpy). The hydrosilyl group acts as a traceless directing group, providing access to a range of 1,1-benzyldiboronate esters in good yields. Transformations of the 1,1-benzyldiboronate ester products include chemoselective Suzuki-Miyaura cross-couplings and synthesis of tetrasubstituted alkenyl boronate esters.
Zirconocene-mediated highly regio- and stereoselective synthesis of multisubstituted olefins starting from 1-alkynylboronates
Nishihara, Yasushi,Miyasaka, Mitsuru,Okamoto, Masanori,Takahashi, Hideki,Inoue, Eiji,Tanemura, Kenki,Takagi, Kentaro
, p. 12634 - 12635 (2008/03/13)
Multisubstituted olefins are efficiently prepared by the zirconocene-mediated regio- and stereoselective coupling between 1-alkynylboronates and ethylene, followed by sequential transformation in moderate to high yields. The proper combination of substrates and reaction conditions is important for high yields. The synthesis of various tetrasubstituted alkenes in a regio- and stereocontrolled manner is described. This methodology has been applied to the synthesis of (Z)-tamoxifen in a concise, regio- and stereoselective manner. This multicomponent coupling strategy involves the characteristics of 1-alkynylboronates toward high selectivities followed by palladium(0)-mediated cross-coupling with aryl halides. Copyright
Stereoselective cross-coupling reaction of 1,1-diboryl-1-alkenes with electrophiles: A highly stereocontrolled approach to 1,1,2-triaryl-1-alkenes
Shimizu, Masaki,Nakamaki, Chihiro,Shimono, Katsuhiro,Schelper, Michael,Kurahashi, Takuya,Hiyama, Tamejiro
, p. 12506 - 12507 (2007/10/03)
Palladium-catalyzed cross-coupling reaction of 1,1-diboryl-1-alkenes with aryl and alkenyl iodides was found to proceed stereoselectively, giving rise to the corresponding mono-coupled product as a single diastereomer with E-configuration. Second coupling of the initial product with another aryl iodide affords diverse triarylalkenes in their stereochemically pure form. This highly stereoselective approach for triarylalkenes allows one to synthesize both diastereomers in one pot from 1,1-diboryl-1-alkenes. Copyright
Diversity-Oriented Synthesis of Tamoxifen-type Tetrasubstituted Olefins
Itami, Kenichiro,Kamei, Toshiyuki,Yoshida, Jun-Ichi
, p. 14670 - 14671 (2007/10/03)
A general synthetic scheme for tamoxifen-type tetrasubstituted olefins based on the novel Cu-catalyzed carbomagnesation across alkynyl(2-pyridyl)silane has been developed. A wide array of electronically and structurally diverse tetrasubstituted olefins can be prepared in a regiocontrolled, stereocontrolled, and diversity-oriented manner. Noteworthy features are that (i) the three aryl groups, which are believed to be important (essential) for anti-estrogenic activity, can be varied at will because they all stem from readily available aryl iodides, and (ii) any stereo- and regioisomers can, in principle, be prepared by simply changing the applying order of aryl iodides into the sequence. Copyright
