Silylboranes as Powerful Tools in Organic Synthesis: Stereo- and Regioselective Reactions with 1,n-Enynes

Synthesis ◽  
2020 ◽  
Vol 52 (21) ◽  
pp. 3129-3139 ◽  
Author(s):  
Christina Moberg

Bismetalated alkenes, accessible by element–element addition to alkynes, are valuable building blocks in organic synthesis, providing wide opportunities for divergent synthesis. Silaboration of alkynes with a pendant olefinic group, catalyzed by group 10 metal complexes, and subsequent transformation of the silicon and boron functional groups give access to densely functionalized 1,3-dienes and 1,3,5-trienes with defined stereo- and regiochemistry, 1,2-dienes, and carbocyclic and heterocyclic products.1 Introduction2 Background3 Reactions with 1,3-Enynes4 Cyclization 1,6-Enynes5 Cyclization 1,7-Enynes6 Cyclization of 1,n-Enynes (n > 7)7 Cyclization of Dienynes and Enediynes8 Cyclization of 1,6-Diynes9 Conclusions

2017 ◽  
Vol 89 (8) ◽  
pp. 1209-1222 ◽  
Author(s):  
Victor I. Saloutin ◽  
Yulia S. Kudyakova ◽  
Marina V. Goryaeva ◽  
Yanina V. Burgart ◽  
Oleg N. Chupakhin

AbstractThe review focuses on the synthesis and chemical properties of polyfluoroalkylated 2-ethoxymethylene-3-oxo esters. The scope and peculiarities of their use as organic reagents in reactions with various N-, C-, O-, mono- and dinucleophiles are discussed in detail. The high reactivity of such derivatives is employed in the construction of enaminoketone, arene and heterocycle frameworks. Particular attention is paid to applications of these building blocks as chemicals for fine organic synthesis, bioactive compounds and metal complexes synthesis.


Synthesis ◽  
2017 ◽  
Vol 49 (24) ◽  
pp. 5307-5319 ◽  
Author(s):  
Chuan Wang

Small heterocycles, such as epoxides, aziridines, and ox­etanes are among the most useful building blocks in organic synthesis. Through electrophilic ring opening of these molecules, various electrophilic functional groups can be installed, which cannot be achieved via classic nucleophilic ring-opening reactions. In this review, the developments of electrophilic ring opening of small heterocycles are surveyed and organized according to the types of metal promoters.1 Introduction2 Electrophilic Ring Opening of Small Heterocycles Using Stoichiometric Metals2.1 Lithium-Mediated Electrophilic Ring Opening of Epoxides and Oxetanes2.2 Chromium-Mediated Electrophilic Ring Opening of Vinyl Epoxides2.3 Tin-Mediated Electrophilic Ring Opening of Vinyl Epoxides2.4 Samarium-Mediated Electrophilic Ring Opening of Vinyl and Alkynyl Epoxides2.5 Titanium-Mediated Electrophilic Ring Opening of Epoxides2.6 Platinum, Palladium, and Nickel-Mediated Electrophilic Ring Opening of 1,1-Dimethyl Ethylene Oxide3 Catalytic Electrophilic Ring Opening of Small Heterocycles3.1 Titanium-Catalyzed Electrophilic Ring Opening of Epoxides3.2 Palladium-Catalyzed Electrophilic Ring Opening of Vinyl and Alkynyl Small Heterocycles3.3 Iron-Catalyzed Electrophilic Ring Opening of Oxetanes3.4 Scandium-Catalyzed Electrophilic Ring Opening of Vinyl Epoxides3.5 Iridium-Catalyzed Electrophilic Ring Opening of 2-Methyl 2-Vinyl­oxiranes3.6 Nickel-Catalyzed Electrophilic Ring Opening of Epoxides and Aziridines3.7 Nickel–Titanium-Cocatalyzed Electrophilic Ring Opening of Epoxides4 Summary


Organics ◽  
2021 ◽  
Vol 2 (3) ◽  
pp. 287-305
Author(s):  
Matthieu Pélingre ◽  
Dindet Steve-Evanes Koffi Teki ◽  
Jamal El-Abid ◽  
Vincent Chagnault ◽  
José Kovensky ◽  
...  

Many preparations of maltooligosaccharides have been described in literature, essentially using enzymatic or biotechnological processes. These compounds, derived from starch, are well-known as prebiotic agents. The use of maltohexa-, hepta-, and octaoses as synthons in organic synthesis was also well documented in literature. They can indeed be obtained as single compounds by the cyclodextrins’ ring-opening. This reaction has been studied for many years, varying the protecting and functional groups and the reaction conditions, leading to functionalized oligomaltoses. These compounds are of wide interest in various fields. They have a strong potential as scaffolds for multivalence in chemobiology, as building blocks for the production of biomimetic pseudo-glycopeptides, as well as monomers for the preparation of materials. In view of the importance of these oligomaltoses, this review focuses on the different methodologies allowing access to them via chemical and enzymatic ring-opening of cyclodextrins.


2021 ◽  
Author(s):  
Bhisma K. Patel ◽  
Tipu Alam ◽  
Amitava Rakshit

In the last few years, the photo-redox process via single-electron transfer (SET) has received substantial attention for the synthesis of targeted organic compounds due to its environmental friendliness and sustainability. Of late visible-light-mediated difunctionalization of alkenes has gained much attention because of its step economy, which allows the consecutive installation of two functional groups across the C=C bond in a single operation. The construction of N-containing compounds has always been important in organic synthesis. Molecules containing C-N bonds are found in many building blocks and are important precursors to other functional groups. Meanwhile, C-N bond formation via the addition of the C=C double bond is gaining prominence. Therefore, considering the influence and synthetic potential of the C-N bond, here we provide a summary of the state of the art on visible-light-driven difunctionalizations of alkene. We hope that the construction of the C-N bond via visible-light-mediated difunctionalization of alkenes will be useful for medicinal and synthetic organic chemists and will inspire further reaction development in this interesting area.


2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Zhusong Cao ◽  
Jianye Li ◽  
Guozhu Zhang

AbstractCyclobutanols are privileged cyclic skeletons in natural products and synthetic building blocks. C(sp3)−H functionalization is a prolonged challenge in organic synthesis. The synthesis of cyclobutanols through double C(sp3)-H bond functionalization remains elusive. Here we report the efficient synthesis of cyclobutanols through intermolecular radical [3 + 1] cascade cyclization, involving the functionalization of two C − H bonds through sequential hydrogen atom transfer. The copper complex reduces the iodomethylsilyl alcohols efficiently under blue-light irradiation to initiate the tandem transformation. The mild reaction tolerates a broad range of functional groups and allows for the facile generation of elaborate polycyclic structures.


Author(s):  
Huanfeng Jiang ◽  
Wanqing Wu ◽  
Ziying Wu ◽  
Miao Hu ◽  
Jianxiao Li

Alkenes are versatile building blocks in modern organic synthesis. In the difunctionalization reactions of alkenes, two functional groups can be simultaneously introduced into the π system. This is an efficient...


2019 ◽  
Author(s):  
De-Wei Gao ◽  
Yang Gao ◽  
Huiling Shao ◽  
Tian-Zhang Qiao ◽  
Xin Wang ◽  
...  

Enantioenriched <i>α</i>-aminoboronic acids play a unique role in medicinal chemistry and have emerged as privileged pharmacophores in proteasome inhibitors. Additionally, they represent synthetically useful chiral building blocks in organic synthesis. Recently, CuH-catalyzed asymmetric alkene hydrofunctionalization has become a powerful tool to construct stereogenic carbon centers. In contrast, applying CuH cascade catalysis to achieve reductive 1,1-difunctionalization of alkynes remains an important, but largely unaddressed, synthetic challenge. Herein, we report an efficient strategy to synthesize <i>α</i>-aminoboronates <i>via </i>CuH-catalyzed hydroboration/hydroamination cascade of readily available alkynes. Notably, this transformation selectively delivers the desired 1,1-heterodifunctionalized product in favor of alternative homodifunctionalized, 1,2-heterodifunctionalized, or reductively monofunctionalized byproducts, thereby offering rapid access to these privileged scaffolds with high chemo-, regio- and enantioselectivity.<br>


2019 ◽  
Author(s):  
Patrick Fier ◽  
Kevin M. Maloney

Herein we describe the development and application of a method for the mild, late-stage conversion of primary sulfonamides to several other other functional groups. These reactions occur via initial reductive deamination of sulfonamides to sulfinates via an NHC-catalyzed reaction of transiently formed <i>N</i>-sulfonylimines. The method described here is tolerant of nearly all common functional groups, as exemplified by the late-stage derivatization of several complex pharmaceutical compounds. Based on the prevalence of sulfonamide-containing drugs and building blocks, we have developed a method to enable sulfonamides to be applied as versatile synthetic handles for synthetic chemsitry.


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