scholarly journals Copper Mediated C(sp2)–H Sulfonylation of Aldehydes using a Catalytic Transient Imine Directing Group

2021 ◽  
Author(s):  
Joe Higham ◽  
James A Bull
Keyword(s):  
Transition State ◽  
Mechanistic Studies ◽  
Type Transition ◽  
Limiting Step ◽  
Group A ◽  
Directing Group

The copper mediated β–C(sp2)–H sulfonylation of benzaldehydes with sulfinate salts is accomplished using β-alanine as a catalytic transient directing group. A broad range of sulfonylated benzaldehydes are prepared us-ing copper fluoride as both copper source and oxidant. Both b-(ortho) and g-(peri)-sulfonylation are demon-strated. Mechanistic studies indicate the turnover limiting step to be a concerted asynchronous C–H cleavage via a Wheland-type transition state.

Synthetic and Mechanistic Studies of a Versatile Heteroaryl Thioether Directing Group for Pd(II) Catalysis

2019 ◽  
Author(s):  
Andrew Romine ◽  
Kin Yang ◽  
Malkanthi Karunananda ◽  
Jason Chen ◽  
Keary Engle
Keyword(s):  
Mechanistic Studies ◽  
Salvianolic Acid ◽  
Wide Range ◽  
Computational Data ◽  
Synthetic Utility ◽  
Directing Group ◽  
High Yields ◽  
Julia Olefination ◽  
Reaction Progress Kinetic Analysis

A weakly coordinating monodentate heteroaryl thioether directing group has been developed for use in Pd(II) catalysis to orchestrate key elementary steps in the catalytic cycle that require conformational flexibility in a manner that is difficult to accomplish with traditional strongly coordinating directing groups. This benzothiazole thioether, (BT)S, directing group can be used to promote oxidative Heck reactivity of internal alkenes providing a wide range of products in moderate to high yields. To demonstrate the broad applicability of this directing group, arene C–H olefination was also successfully developed. Reaction progress kinetic analysis provides insights into the role of the directing group in each reaction, which is supplemented with computational data for the oxidative Heck reaction. Furthermore, this (BT)S directing group can be transformed into a number of synthetically useful functional groups, including a sulfone for Julia olefination, allowing it to serve as a “masked olefin” directing group in synthetic planning. In order to demonstrate this synthetic utility, natural products (+)-salvianolic acid A and salvianolic acid F are formally synthesized using the (BT)S directed C–H olefination as the key step.

scholarly journals Asymmetric Addition of Allylsilanes to Aldehydes – A Cr/Photoredox Dual Catalytic Approach Complementing the Hosomi–Sakurai Reaction

2021 ◽  
Author(s):  
Felix Schäfers ◽  
Subhabrata Dutta ◽  
Roman Kleinmans ◽  
Christian Mück-Lichtenfeld ◽  
Frank Glorius
Keyword(s):  
Organic Chemistry ◽  
Transition State ◽  
Bioactive Compound ◽  
General Strategy ◽  
Acid Activation ◽  
Mechanistic Studies ◽  
Mild Conditions ◽  
Homoallylic Alcohols ◽  
Synthetic Utility ◽  
Fundamental Transformation

The allylation of aldehydes is a fundamental transformation in synthetic organic chemistry. Among the multitude of available reagents, especially allylsilanes have been established as preferred allyl source. As initially reported by Hosomi & Sakurai, these non-toxic and highly stable reagents add to carbonyls via an open transition state upon Lewis acid activation. Herein, we report a general strategy to access a variety of valuable homoallylic alcohols in opposite chemo- and diastereoselectivity to the established Hosomi–Sakurai conditions by switching to photocatalytic activation in combination with a closed transition state (Chromium catalysis). Moreover, this dual catalytic approach displays a straightforward way to introduce excellent levels of enantioselectivity and its mild conditions allow for a broad substrate scope including chiral boron-substituted products as a highlight. To emphasize the synthetic utility, our method was applied as the key step in the synthesis of a bioactive compound and in the late-stage functionalization of steroid derivatives. Detailed mechanistic studies and DFT calculations hint towards an unprecedented photo-initiated chain being operative.

Carbon Dioxide-Driven Palladium-Catalyzed C–H Activation of Amines: A Unified Approach for the Arylation of Aliphatic and Aromatic Primary and Secondary Amines

Synlett ◽  
2019 ◽  
Vol 30 (05) ◽  
pp. 519-524 ◽  
Author(s):  
Michael Young ◽  
Mohit Kapoor ◽  
Pratibha Chand-Thakuri ◽  
Justin Maxwell ◽  
Daniel Liu ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Bond Activation ◽  
Secondary Amines ◽  
Activation Process ◽  
Unified Approach ◽  
Benzylic Amines ◽  
Palladium Catalyzed ◽  
Group A ◽  
Directing Group ◽  
Site Selective

Amines are an important class of compounds in organic chemistry and serve as an important motif in various industries, including pharmaceuticals, agrochemicals, and biotechnology. Several methods have been developed for the C–H functionalization of amines using various directing groups, but functionalization of free amines remains a challenge. Here, we discuss our recently developed carbon dioxide driven highly site-selective γ-arylation of alkyl- and benzylic amines via a palladium-catalyzed C–H bond-activation process. By using carbon dioxide as an inexpensive, sustainable, and transient directing group, a wide variety of amines were arylated at either γ-sp3 or sp2 carbon–hydrogen bonds with high selectivity based on substrate and conditions. This newly developed strategy provides straightforward access to important scaffolds in organic and medicinal chemistry without the need for any expensive directing groups.1 Introduction2 C(sp3)–H Arylation of Aliphatic Amines3 C(sp2)–H Arylation of Benzylamines4 Mechanistic Questions5 Future Outlook

scholarly journals Pd-catalyzed intramolecular addition of active methylene compounds to alkynes with subsequent cross-coupling with (hetero)aryl halides

RSC Advances ◽  
2019 ◽  
Vol 9 (68) ◽  
pp. 40152-40167 ◽  
Author(s):  
Aleksandra Błocka ◽  
Paweł Woźnicki ◽  
Marek Stankevič ◽  
Wojciech Chaładaj
Keyword(s):  
Functional Group ◽  
Cross Coupling ◽  
Aryl Halides ◽  
Mechanistic Studies ◽  
Rate Limiting Step ◽  
Limiting Step ◽  
Active Methylene Compounds ◽  
Tandem Cyclization ◽  
Rate Limiting ◽  
Active Methylene

A tandem cyclization/coupling of acetylenic active methylene compounds with aryl halides features broad scope and excellent functional group compatibility. Mechanistic studies identified 5-exo-dig cyclization as the rate limiting step.

Cobalt-promoted selective arylation of benzamides and acrylamides with arylboronic acids

2016 ◽  
Vol 14 (47) ◽  
pp. 11070-11075 ◽  
Author(s):  
Liang Hu ◽  
Qingwen Gui ◽  
Xiang Chen ◽  
Ze Tan ◽  
Gangguo Zhu
Keyword(s):  
Copper Salts ◽  
Notable Feature ◽  
Arylboronic Acids ◽  
Group A ◽  
Directing Group

A novel cobalt-promoted arylation of aryl C–H bonds with arylboronic acids has been realized by using 8-aminoquinoline as the directing group. A notable feature of this newly developed protocol is that acrylamides, which cannot be arylated using copper salts as the promoter, can also be efficiently arylated.

Epoxy and Oxidoannulene Oxidation Mechanisms of Fused-Pentagon Chlorofullerenes: Oxides Linked by a Pirouette-Type Transition State

2017 ◽  
Vol 82 (13) ◽  
pp. 6541-6549 ◽  
Author(s):  
Qiao-Zhi Li ◽  
Jia-Jia Zheng ◽  
Ling He ◽  
Xiang Zhao ◽  
Shigeru Nagase
Keyword(s):  
Transition State ◽  
Type Transition ◽  
Oxidation Mechanisms

ChemInform Abstract: The Pyridyldiisopropylsilyl Group: A Masked Functionality and Directing Group for Monoselective ortho-Acyloxylation and ortho-Halogenation Reactions of Arenes.

ChemInform ◽  
2011 ◽  
Vol 42 (40) ◽  
pp. no-no
Author(s):  
Chunhui Huang ◽  
Natalia Chernyak ◽  
Alexander S. Dudnik ◽  
Vladimir Gevorgyan
Keyword(s):  
Group A ◽  
Directing Group
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