Abstract:A Cerium(IV)‐promoted phosphinoylation‐nitratation of alkenes is established under mild conditions. In this process, Ceric ammonium nitrate (CAN) acts as a cheap phosphorus‐radical initiator, as well as a nitrate donor. Various β‐nitrooxyphosphonates are delivered in high yield in a one‐pot manner.magnified image
“…In 2018, Deng's group reported organocatalytic asymmetric aza-Friedel-Crafts reaction of pyrazolinone ketimines with hydroxyindoles to access chiral indolepyrazolinone derivatives (Scheme 1d). [11] Despite this elegant progress, the realization of asymmetric reaction of pyrazolinone ketimines with different diversities of nucleophilic reagents remains highly desirable and an important goal. On the other hand, the asymmetric decarboxylative Mannich reaction of -ketoacids [12] with imines has drawn a great attention of synthetic chemists, [13] because it provides a powerful approach to achieve -amino ketones, which are valuable synthetic intermediates to convert into other versatile building blocks, such asamino alcohols, amines, and -amino acid derivatives.…”
An organocatalytic enantioselective decarboxylative Mannich reaction of pyrazolin‐5‐one derived ketimines with β‐ketoacids using quinine‐derived bifunctional squaramide as a catalyst has been developed. With the developed protocol, a series of chiral β‐amino ketone‐pyrazolinone derivatives were obtained in excellent yields (up to 99 %) with good enantioselectivities (up to 94:6 er). The enantioselective decarboxylative aldol reaction of pyrazole‐4,5‐dione with β‐ketoacids was also realized under the standard reaction conditions.
“…In 2018, Deng's group reported organocatalytic asymmetric aza-Friedel-Crafts reaction of pyrazolinone ketimines with hydroxyindoles to access chiral indolepyrazolinone derivatives (Scheme 1d). [11] Despite this elegant progress, the realization of asymmetric reaction of pyrazolinone ketimines with different diversities of nucleophilic reagents remains highly desirable and an important goal. On the other hand, the asymmetric decarboxylative Mannich reaction of -ketoacids [12] with imines has drawn a great attention of synthetic chemists, [13] because it provides a powerful approach to achieve -amino ketones, which are valuable synthetic intermediates to convert into other versatile building blocks, such asamino alcohols, amines, and -amino acid derivatives.…”
An organocatalytic enantioselective decarboxylative Mannich reaction of pyrazolin‐5‐one derived ketimines with β‐ketoacids using quinine‐derived bifunctional squaramide as a catalyst has been developed. With the developed protocol, a series of chiral β‐amino ketone‐pyrazolinone derivatives were obtained in excellent yields (up to 99 %) with good enantioselectivities (up to 94:6 er). The enantioselective decarboxylative aldol reaction of pyrazole‐4,5‐dione with β‐ketoacids was also realized under the standard reaction conditions.
“…Trapping of carbocation by amines afford corresponding α,β-phosphinoamination products 37. Wang and coworkers reported Ce-catalyzed phosphinoylation and nitration reactions of alkenes (Scheme 21) [43]. CAN (NH 4 ) 2 Ce(NO 3 ) 6 was used as P-radical initiator and also nitrate donor to afford β-nitrooxyphosphonates 36.…”
Section: Scheme 20 Phosphinoylation and Cyanylation Of Alkenesmentioning
Popular and readily available alkenes and alkynes are good substrates for the preparation of functionalized molecules through radical and/or ionic addition reactions. Difunctionalization is a topic of current interest due to its high efficiency, substrate versatility, and operational simplicity. Presented in this article are radical addition followed by oxidation and nucleophilic addition reactions for difunctionalization of alkenes or alkynes. The difunctionalization could be accomplished through 1,2-addition (vicinal) and 1,n-addition (distal or remote) if H-atom or group-transfer is involved in the reaction process. A wide range of moieties, such as alkyl (R), perfluoroalkyl (Rf), aryl (Ar), hydroxy (OH), alkoxy (OR), acetatic (O2CR), halogenic (X), amino (NR2), azido (N3), cyano (CN), as well as sulfur- and phosphorous-containing groups can be incorporated through the difunctionalization reactions. Radicals generated from peroxides or single electron transfer (SET) agents, under photoredox or electrochemical reactions are employed for the reactions.
“…Huge progress has been achieved in oxidative transformations (Fig. 1a) 18–21 , in which the electron-rich alkyl radicals, in situ generated through addition of phosphonyl radicals to alkenes, are oxidized to alkyl cations and then trapped by the nucleophilic components. However, the redox-neutral difunctionalization of alkenes with H-P(O) compounds remains very rare 22 .Fig.…”
Section: Introductionmentioning
confidence: 99%
“…We envisioned that the simultaneous incorporation of both phosphonyl and carboxyl groups via selective difunctionalization of enamides and other alkenes would serve as an ideal route to deliver important β-phosphono carboxylic acids, including β-phosphono α-amino acids. Different from the above mentioned oxidative functionalization of the generated alkyl radicals 18–21 , we hypothesized that reduction of such key alkyl radicals to anions, which might undergo nucleophilic attack to CO 2 , could realize redox-neutral difunctionalization of alkenes with H-P(O) compounds. To the best of our knowledge, this strategy has never been realized to generate such valuable targets.…”
Catalytic difunctionalization of alkenes has been an ideal strategy to generate structurally complex molecules with diverse substitution patterns. Although both phosphonyl and carboxyl groups are valuable functional groups, the simultaneous incorporation of them via catalytic difunctionalization of alkenes, ideally from abundant, inexpensive and easy-to-handle raw materials, has not been realized. Herein, we report the phosphonocarboxylation of alkenes with CO
2
via visible-light photoredox catalysis. This strategy is sustainable, general and practical, providing facile access to important β-phosphono carboxylic acids, including structurally complex unnatural α-amino acids. Diverse alkenes, including enamides, styrenes, enolsilanes and acrylates, undergo such reactions efficiently under mild reaction conditions. Moreover, this method represents a rare example of redox-neutral difunctionalization of alkenes with H-P(O) compounds, including diaryl- and dialkyl- phosphine oxides and phosphites. Importantly, these transition-metal-free reactions also feature low catalyst loading, high regio- and chemo-selectivities, good functional group tolerance, easy scalability and potential for product derivatization.
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