scholarly journals Selective sulfonylation and isonitrilation of para-quinone methides employing TosMIC as a source of sulfonyl group or isonitrile group

2021 ◽  
Vol 17 ◽  
pp. 2822-2831
Author(s):  
Chuanhua Qu ◽  
Run Huang ◽  
Yong Li ◽  
Tong Liu ◽  
Yuan Chen ◽  
...  
Keyword(s):  
Natural Products ◽  
Dual Role ◽  
Quinone Methides ◽  
Sulfonyl Group ◽  
Synthetic Utility ◽  
Zinc Iodide

Chemoselective sulfonylation and isonitrilation reactions for the divergent synthesis of valuable diarylmethyl sulfones and isonitrile diarylmethanes starting from easy-to-synthesize para-quinone methides (p-QMs) and commercially abundant p-toluenesulfonylmethyl isocyanide (TosMIC) by using respectively zinc iodide and 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) as catalysts were developed. The distinguishing feature of this method is that TosMIC plays a dual role from the same substrates in the reaction: as a sulfonyl source or as an isonitrile source. The synthetic utility of this protocol was also demonstrated in the synthesis of difluoroalkylated diarylmethane 5 and diarylmethane ketone derivatives 6 and 7, which are important core structures in natural products and medicines.

Alkynyl Prins and Alkynyl Aza-Prins Annulations: Scope and Synthetic Applications

Synthesis ◽  
2020 ◽  
Vol 52 (14) ◽  
pp. 1991-2007 ◽  
Author(s):  
Alison J. Frontier ◽  
Shukree Abdul-Rashed ◽  
Connor Holt
Keyword(s):  
Natural Products ◽  
Small Molecules ◽  
Natural Product ◽  
Natural Product Synthesis ◽  
Pericyclic Reactions ◽  
Prins Reaction ◽  
Prins Cyclization ◽  
Synthetic Utility ◽  
Cascade Processes ◽  
Saturated Heterocycles

This review focuses on alkynyl Prins and alkynyl aza-Prins cyclization­ processes, which involve intramolecular coupling of an alkyne with either an oxocarbenium or iminium electrophile. The oxocarbenium or iminium species can be generated through condensation- or elimination-type processes, to achieve an overall bimolecular annulation that enables the synthesis of both oxygen- and nitrogen-containing­ saturated heterocycles with different ring sizes and substitution patterns. Also discussed are cascade processes in which alkynyl Prins heterocyclic adducts react to trigger subsequent pericyclic reactions, including [4+2] cycloadditions and Nazarov electrocyclizations, to rapidly construct complex small molecules. Finally, examples of the use of alkynyl Prins and alkynyl aza-Prins reactions in the synthesis of natural products are described. The review covers the literature through the end of 2019.1 Introduction1.1 Alkyne-Carbonyl Coupling Pathways1.2 Coupling/Cyclization Cascades Using the Alkynyl Prins Reaction2 Alkynyl Prins Annulation (Oxocarbenium Electrophiles)2.1 Early Work2.2 Halide as Terminal Nucleophile2.3 Oxygen as Terminal Nucleophile2.4 Arene as Terminal Nucleophile (Intermolecular)2.5 Arene Terminal Nucleophile (Intramolecular)2.6 Cyclizations Terminated by Elimination3 Synthetic Utility of Alkynyl Prins Annulation3.1 Alkynyl Prins-Mediated Synthesis of Dienes for a [4+2] Cyclo­- addition­-Oxidation Sequence3.2 Alkynyl Prins Cyclization Adducts as Nazarov Cyclization Precursors3.3 Alkynyl Prins Cyclization in Natural Product Synthesis4 Alkynyl Aza-Prins Annulation4.1 Iminium Electrophiles4.2 Activated Iminium Electrophiles5 Alkynyl Aza-Prins Cyclizations in Natural Product Synthesis6 Summary and Outlook

4π electrocyclisation in domino processes: contemporary trends and synthetic applications towards natural products

2015 ◽  
Vol 13 (44) ◽  
pp. 10774-10796 ◽  
Author(s):  
Nadeem S. Sheikh
Keyword(s):  
Natural Products ◽  
Domino Reactions ◽  
Bioactive Natural Products ◽  
Mechanistic Insight ◽  
Synthetic Utility

Recent most illustrative examples dealing with 4π electrocyclisation in domino reactions, along with a precise mechanistic insight and its synthetic utility towards bioactive natural products are concisely reviewed.

Synthesis of 3-(4′-Methoxyphenyl)-2,2,4,4-Tetramethylpentane and Some Cyclic Analogs

1986 ◽  
Vol 39 (12) ◽  
pp. 2095 ◽  
Author(s):  
DJ Collins ◽  
HA Jacobs
Keyword(s):  
Methanesulfonic Acid ◽  
Similar Reaction ◽  
Reaction Sequence ◽  
Quinone Methides ◽  
Hydride Reduction ◽  
Lithium Aluminium ◽  
Clemmensen Reduction ◽  
Analogous Manner ◽  
Hydrolysis Of ◽  
Zinc Iodide

Reaction of 1-methoxy-2-methyl-1-trimethylsilyloxyprop-1-ene (8) with 1-acetoxy-1-(4′-methoxyphenyl)-2,2-dimethylpropane (7b) in the presence of zinc iodide gave 84% of methyl 3-(4′methoxyphenyl)-2,2,4,4- tetramethylpentanoate (9a), which was reduced with lithium aluminium hydride to 3-(4′-methoxyphenyl)-2,2,4,4-tetramethylpentan-1-ol(12a). Hydride reduction of the derived tosylate (12b) afforded 3-(4′-methoxyphenyl )-2,2,4,4-tetramethylpentane (5b) which upon demethylation yielded the corresponding phenol (10a). In an analogous manner, 1-acetoxy-1-(4′-methoxyphenyl)-2-methylpropane (7d) was converted into 3- (4′-hydroxyphenyl)-2,2,4-trimethylpentane (10b). By a similar reaction sequence, 6-methoxy-2,2-dimethyl-3,4- dihydronaphthalen-1(2H)-one (14) was transformed into 6-hydroxy-2,2- dimethyl-1-(1′,1′-dimethylethyl)-1,2,3,4-tetrahydronaphthalene (16b). Hydrolysis of the ester (9a) and cyclization of the resulting carboxylic acid (19) by treatment with methanesulfonic acid at 20° for 18 h afforded 3-(1′, 1′-dimethylethyl)-6-methoxy-2,2-dimethyl-2,3-dihydro-1H-inden-1-one (20). Clemmensen reduction of this followed by demethylation yielded 1-(1′,1′-dimethylethyl)-2,2-dimethyl-2,3-dihydro-1H-inden-5-ol (21b). Attempts to oxidize the phenols (10a), (10b), (16b) and (21b) to the corresponding quinone methides by conventional methods failed.

Synthesis of Malononitrile-Substituted Diarylmethines via 1,6-Addition of Masked Acyl Cyanides to para-Quinone Methides

Synthesis ◽  
2017 ◽  
Vol 50 (04) ◽  
pp. 872-880 ◽  
Author(s):  
Dieter Enders ◽  
Kun Zhao ◽  
Ying Zhi ◽  
Ai Wang
Keyword(s):  
Bioactive Compounds ◽  
Efficient Method ◽  
Conjugate Addition ◽  
Quinone Methides ◽  
Mild Conditions ◽  
Synthetic Utility

An efficient method for the synthesis of malononitrile-substituted­ diarylmethines through 1,6-conjugate addition of para-quinone­ methides with masked acyl cyanide (MAC) reagents has been developed. Under mild conditions, the scalable reaction occurs in good to excellent yields providing a straightforward access to a series of malononitrile-substituted diarylmethines. The synthetic utility of this protocol has been demonstrated in the synthesis of bioactive compounds.

Iridium-Catalyzed Asymmetric Umpolung Allylation of N-Fluor­enyl Imines to Prepare 1,4-Disubstituted Homoallylic Amines

Synlett ◽  
2017 ◽  
Vol 28 (16) ◽  
pp. 2051-2056 ◽  
Author(s):  
Dawen Niu ◽  
Liqiang Wan ◽  
Lan Tian ◽  
Jie Liu
Keyword(s):  
Natural Products ◽  
Cope Rearrangement ◽  
Allylic Substitution ◽  
Reaction Discovery ◽  
Homoallylic Amines ◽  
Synthetic Utility ◽  
Reaction Proceeds ◽  
Conventional Methods

The discovery and development of an Ir-catalyzed asymmetric umpolung allylation of imines is discussed here. This method produces 1,4-disubstituted homoallylic amines, a class of compounds that are difficult to access by conventional methods. This reaction proceeds through a sequence involving an allylation and a 2-aza-Cope rearrangement event. The unique mechanistic feature of this reaction could be the reason for its broad substrate scope. The products of this reaction are useful intermediates for various bioactive and natural products. Besides its immediate synthetic utility, we expect this transformation to inspire the development of other umpolung functionalizations of imines and Ir-catalyzed asymmetric allylic substitution (AAS) reactions.1 Introduction2 Reaction Discovery3 Substrate Scope4 Conclusion

One-pot synthesis of carbazoles via tandem C–C cross-coupling and reductive amination

2016 ◽  
Vol 14 (1) ◽  
pp. 122-130 ◽  
Author(s):  
Deuk-Young Goo ◽  
Sang Kook Woo
Keyword(s):  
Natural Products ◽  
Reductive Amination ◽  
Bond Formation ◽  
Cross Coupling ◽  
Synthetic Route ◽  
One Pot ◽  
Highly Efficient ◽  
One Pot Synthesis ◽  
Synthetic Utility

We have developed a highly efficient synthetic route to carbazoles that employs sequential C–C/C–N bond formation via Suzuki cross-coupling and Cadogan cyclization. The developed method is compatible with electron neutral, rich or deficient substrates. The synthetic utility of this method was demonstrated by the concise syntheses of four natural products.

Ligand-Accelerated Non-Directed C–H Cyanation of Arenes

2018 ◽  
Author(s):  
Luoyan Liu ◽  
Kap-Sun Yeung ◽  
jin-quan yu
Keyword(s):  
Natural Products ◽  
Bond Cleavage ◽  
Drug Molecules ◽  
Kinetic Isotope ◽  
Rate Limiting Step ◽  
Limiting Step ◽  
Broad Scope ◽  
Synthetic Utility ◽  
Rate Limiting

<p>We herein report the first example of a 2-pyridone accelerated non-directed C−H cyanation with an arene as the limiting reagent. This protocol is compatible with a broad scope of arenes, including advanced intermediates, drug molecules, and natural products. A kinetic isotope experiment (k<sub>H</sub>/k<sub>D</sub> = 4.40) indicates that the C–H bond cleavage is the rate-limiting step. Also, the reaction is readily scalable, further showcasing the synthetic utility of this method.<i></i></p>

Recent applications of the hetero Diels–Alder reaction in the total synthesis of natural products

RSC Advances ◽  
2015 ◽  
Vol 5 (123) ◽  
pp. 101999-102075 ◽  
Author(s):  
Majid M. Heravi ◽  
Tahereh Ahmadi ◽  
Mahdieh Ghavidel ◽  
Bahareh Heidari ◽  
Hoda Hamidi
Keyword(s):  
Organic Chemistry ◽  
Natural Products ◽  
Total Synthesis ◽  
Alder Reaction ◽  
Diels Alder ◽  
Diels Alder Reaction ◽  
Synthetic Utility

The synthetic utility and potential power of the Diels–Alder (D–A) reaction in organic chemistry is evident.

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