scholarly journals Synthesis of Sulfilimines Enabled by Copper-Catalyzed S-Arylation of Sulfenamides

2021 ◽  
Author(s):  
qingjin liang ◽  
Lucille wells ◽  
kaiming han ◽  
shufeng chen ◽  
Marisa Kozlowski ◽  
...  
Keyword(s):  
Oxidation State ◽  
Functional Group ◽  
Bond Formation ◽  
Sulfur Oxidation ◽  
Environmentally Benign ◽  
Protecting Groups ◽  
Synthetic Route ◽  
Alkyl Aryl ◽  
Coupling Procedure ◽  
Type Coupling

Abstract Herein, an unprecedented synthetic route to sulfilimines via a copper-catalyzed Chan-Lam-type coupling of sulfenamides is presented. A key to success in this novel transformation is the chemoselective S-arylation of S(II) sulfenamides to form the S(IV) sulfilimines, overriding the competitive C-N bond formation that does not require a change in sulfur oxidation state. The mild and environmentally benign catalytic conditions enable broad functional group compability. A variety of diaryl or alkyl aryl sulfilimines could be efficiently prepared. The Chan-Lam coupling procedure could also tolerate alkenylboronic acids as coupling partners to afford alkenyl aryl sulfilimines, a class of scaffolds which cannot be directly synthesized via conventional imination strategies. The benzoyl protecting groups could be conveniently removed from the product which, in turn, could be readily transformed to several S(IV) and S(IV) derivatives.

Modern Organic Synthesis in the Laboratory

2008 ◽  
Author(s):  
Jie Jack Li ◽  
Chris Limberakis ◽  
Derek A. Pflum
Keyword(s):  
Organic Chemistry ◽  
Graduate Students ◽  
Organic Synthesis ◽  
Functional Group ◽  
Bond Formation ◽  
Reaction Conditions ◽  
Carbon Bond ◽  
Oxidation Reduction ◽  
Carbon Carbon Bond ◽  
Daunting Task

Searching for reaction in organic synthesis has been made much easier in the current age of computer databases. However, the dilemma now is which procedure one selects among the ocean of choices. Especially for novices in the laboratory, it becomes a daunting task to decide what reaction conditions to experiment with first in order to have the best chance of success. This collection intends to serve as an "older and wiser lab-mate" one could have by compiling many of the most commonly used experimental procedures in organic synthesis. With chapters that cover such topics as functional group manipulations, oxidation, reduction, and carbon-carbon bond formation, Modern Organic Synthesis in the Laboratory will be useful for both graduate students and professors in organic chemistry and medicinal chemists in the pharmaceutical and agrochemical industries.

scholarly journals Kinetic resolution of indolines by asymmetric hydroxylamine formation

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Gang Wang ◽  
Ran Lu ◽  
Chuangchuang He ◽  
Lei Liu
Keyword(s):  
Hydrogen Peroxide ◽  
Chemical Synthesis ◽  
Late Stage ◽  
Kinetic Resolution ◽  
High Efficiency ◽  
Bond Formation ◽  
Bioactive Molecules ◽  
Environmentally Benign ◽  
Secondary Amines

AbstractCatalytic kinetic resolution of amines represents a longstanding challenge in chemical synthesis. Here, we described a kinetic resolution of secondary amines through oxygenation to produce enantiopure hydroxylamines involving N–O bond formation. The economic and practical titanium-catalyzed asymmetric oxygenation with environmentally benign hydrogen peroxide as oxidant is applicable to a range of racemic indolines with multiple stereocenters and diverse substituent patterns in high efficiency with efficient chemoselectivity and enantio-discrimination. Late-stage asymmetric oxygenation of bioactive molecules that are otherwise difficult to synthesize was also explored.

scholarly journals Selenium– and tellurium–halogen reagents

2018 ◽  
Vol 3 (12) ◽  
Author(s):  
Tristram Chivers ◽  
Risto S. Laitinen
Keyword(s):  
Oxidation State ◽  
Halogen Bond ◽  
The Other ◽  
Oxidation States ◽  
Alkyl Aryl ◽  
Organic Selenium ◽  
Formal Oxidation State ◽  
Wide Range ◽  
Inorganic And Organic

Abstract Selenium and tellurium form binary halides in which the chalcogen can be in formal oxidation states (IV), (II) or (I). They are versatile reagents for the preparation of a wide range of inorganic and organic selenium and tellurium compounds taking advantage of the reactivity of the chalcogen–halogen bond. With the exception of the tetrafluorides, the tetrahalides are either commercially available or readily prepared. On the other hand, the low-valent species, EX2 (E = Se, Te; X = Cl, Br) and E2X2 (E = Se, Te; X = Cl, Br) are unstable with respect to disproportionation and must be used as in situ reagents. Organoselenium and tellurium halides are well-known in oxidation states (IV) and (II), as exemplified by REX3, R2EX2 and REX (R = alkyl, aryl; E = Se, Te; X = F, Cl, Br, I); mixed-valent (IV/II) compounds of the type RTeX2TeR are also known. This chapter surveys the availability and/or preparative methods for these widely used reagents followed by examples of their applications in synthetic inorganic and organic selenium and tellurium chemistry. For both the binary halides and their organic derivatives, the discussion is subdivided according to the formal oxidation state of the chalcogen.

scholarly journals The Efficient Synthesis of Azasugars from Pentoses

2021 ◽  
Author(s):  
◽  
Michael Meijlink
Keyword(s):  
Clinical Trials ◽  
Biological Properties ◽  
Protecting Groups ◽  
Synthetic Route ◽  
Efficient Synthesis ◽  
Atom Economy ◽  
Total Syntheses ◽  
Structural Analogues ◽  
Original Procedure ◽  
Synthetic Routes

<p>Azasugars [e.g., 1-deoxy-aza-xylopyranose (1) Figure 1] are structural analogues of sugars [e.g., α-D-xylopyranose (2)] where the ring oxygen is substituted by a nitrogen atom. The resemblance of azasugars to their carbohydrate counterparts gives them various biological properties, such as the inhibition of glycosidase and glycosyltransferase enzymes, and as such, these compounds have been in clinical trials for the treatment of AIDS, diabetes,and cancer. Synthetic routes to azasugars have often involved the use of protecting groups, and therefore have generally reduced efficiency by requiring additional steps to apply or remove protecting groups or requiring adjustment of stereochemistry during the synthesis. This thesis presents the first example of a synthesis of four sterochemically different piperidine triols through a four-step methodology minimising the use of protecting groups starting from pentoses. The synthesis of D-xylose derived (3R,4r,5S)-piperidine triol was previously obtained in 40% yield over five steps, but was afforded in 45% overall yield over four steps using the methodology described within this thesis. Next, D-ribose derived (3R,4s,5S)-piperidine triol was obtained in 40% overall yield over four steps, which afforded a vast improvement on the previous most efficient synthetic route obtaining the azasugar in 24% yield over four steps. This four-step three-pot methodology has thus allowed for the synthesis of these piperidine triols in overall yields ranging from 4-69%, surpassing previous total syntheses in efficiency and improving overall atom economy. To further probe the applicability of the methodology, N-alkyl analogues (such as butyl-, phenylethyl-, and hydroxyethyl-analogues) of all four different piperidine triols were synthesised in comparable or greater overall yields compared to literature reports without any required adaptation to the original procedure. Included in these N-alkyl analogues are seven novel azasugars which were obtained in overall yields ranging from 6-35%.</p>

One-Pot Access to 4-Aryl-2-arylacetoxynaphthalenes via Benz­annulation of Oxygenated Arylacetic Acids and Alkyl Aryl Ketones

Synthesis ◽  
2020 ◽  
Vol 52 (07) ◽  
pp. 1035-1046 ◽  
Author(s):  
Meng-Yang Chang ◽  
Shin-Mei Chen ◽  
Yu-Ting Hsiao
Keyword(s):  
Bond Formation ◽  
Trifluoroacetic Anhydride ◽  
Ring Closure ◽  
One Pot ◽  
Alkyl Aryl ◽  
Highly Effective ◽  
Aryl Ketones ◽  
Arylacetic Acids ◽  
Plausible Mechanism

Trifluoroacetic anhydride mediated one-pot intermolecular formal (4+2) benzannulation of oxygenated arylacetic acids with alkyl aryl ketones provides 4-aryl-2-arylacetoxynaphthalenes in moderate to good yields in the presence of H3PO4 in an open-vessel in a straightforward procedure. A plausible mechanism is proposed and discussed. This protocol provides a highly effective ring-closure via two carbon–carbon (C–C) and one carbon–oxygen (C–O) bond-formation events.

scholarly journals A general method for site-selective Csp3–S bond formation via cooperative catalysis

2020 ◽  
Vol 11 (5) ◽  
pp. 1276-1282 ◽  
Author(s):  
Yuman Qin ◽  
Yujie Han ◽  
Yongzhen Tang ◽  
Junfa Wei ◽  
Mingyu Yang
Keyword(s):  
Functional Group ◽  
Bond Formation ◽  
Aliphatic Amines ◽  
Cooperative Catalysis ◽  
Site Selective ◽  
General Method

A copper-catalyzed site-selective thiolation of Csp3–H bonds of aliphatic amines was developed. The method features a broad substrate scope and good functional group tolerance.

scholarly journals Iron-Catalyzed C(sp2)–C(sp3) Cross-Coupling of Aryl Chlorobenzoates with Alkyl Grignard Reagents

Molecules ◽  
2020 ◽  
Vol 25 (1) ◽  
pp. 230 ◽  
Author(s):  
Elwira Bisz ◽  
Michal Szostak
Keyword(s):  
Organic Synthesis ◽  
Nucleophilic Addition ◽  
Functional Group ◽  
High Selectivity ◽  
Cross Coupling ◽  
Environmentally Benign ◽  
Grignard Reagents ◽  
High Importance ◽  
Iron Salts ◽  
The Cross

Aryl benzoates are compounds of high importance in organic synthesis. Herein, we report the iron-catalyzed C(sp2)–C(sp3) Kumada cross-coupling of aryl chlorobenzoates with alkyl Grignard reagents. The method is characterized by the use of environmentally benign and sustainable iron salts for cross-coupling in the catalytic system, employing benign urea ligands in the place of reprotoxic NMP (NMP = N-methyl-2-pyrrolidone). It is notable that high selectivity for the cross-coupling is achieved in the presence of hydrolytically-labile and prone to nucleophilic addition phenolic ester C(acyl)–O bonds. The reaction provides access to alkyl-functionalized aryl benzoates. The examination of various O-coordinating ligands demonstrates the high activity of urea ligands in promoting the cross-coupling versus nucleophilic addition to the ester C(acyl)–O bond. The method showcases the functional group tolerance of iron-catalyzed Kumada cross-couplings.

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