Alkaloid-Catalyzed Enantioselective [3 + 2] Cycloaddition of Ketenes and Azomethine Imines

Mondal, Mukulesh; Wheeler, Kraig A.; Kerrigan, Nessan J.

doi:10.1021/acs.orglett.6b02038

Cited by 33 publications

(24 citation statements)

References 23 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…With the acetoxy group, a markedly improved trans -diastereoselectivity was observed ( dr 12:1 to 27:1). If pseudo enantiomeric catalyst C10 was applied, enantiomeric (2 S ,3 R )-bicyclic cycloadducts 91 were obtained, retaining the same level of stereoselectivity ( Scheme 29 ) [ 51 ].…”

Section: Synthesis Of Pyrazolidinesmentioning

confidence: 99%

Synthesis of Non-Racemic Pyrazolines and Pyrazolidines by [3+2] Cycloadditions of Azomethine Imines

et al. 2017

View full text Add to dashboard Cite

Asymmetric [3+2] cycloadditions of azomethine imines comprise a useful synthetic tool for the construction of pyrazole derivatives with a variable degree of saturation and up to three stereogenic centers. As analogues of pyrrolidines and imidazolidines that are abundant among natural products, pyrazoline and pyrazolidine derivatives represent attractive synthetic targets due to their extensive applications in the chemical and medicinal industries. Following the increased understanding of the mechanistic aspect of metal-catalyzed and organocatalyzed [3+2] cycloadditions of 1,3-dipoles gained over recent years, significant strides have been taken to design and develop new protocols that proceed efficiently under mild synthetic conditions and duly benefit from superior functional group tolerance and selectivity. In this review, we represent the current state of the art in this field and detailed methods for the synthesis of non-racemic pyrazolines and pyrazolidines via [3+2] metal and organocatalyzed transformations reported since the seminal work of Kobayashi et al. and Fu et al. in 2002 and 2003 up to the end of year 2017.

show abstract

Section: Synthesis Of Pyrazolidinesmentioning

confidence: 99%

Synthesis of Non-Racemic Pyrazolines and Pyrazolidines by [3+2] Cycloadditions of Azomethine Imines

et al. 2017

View full text Add to dashboard Cite

show abstract

“…[6] This interesting approach gave the products in satisfactory to high yield, moderate to high diastereoselectivity and high enantiocontrol. [6] This interesting approach gave the products in satisfactory to high yield, moderate to high diastereoselectivity and high enantiocontrol.…”

mentioning

confidence: 97%

“…The Kerrigan's group recently disclosed a diastereo-and enantioselective version based on the in situ generation of ketenes from overstoichiometric amounts of acyl chlorides and Hü nig base, reacted at low temperature with N,N'-cyclic azomethine imines, in the presence of Cinchona alkaloids derived dimers as catalysts (Scheme 1b). [6] This interesting approach gave the products in satisfactory to high yield, moderate to high diastereoselectivity and high enantiocontrol. Protocols reported in Scheme 1a,b relied 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 on the generation of sensitive species under controlled conditions.…”

mentioning

confidence: 97%

“…[6,15] Hoping to fill a gap in the synthetic arsenal, previously reported unreactive azomethine imines 2, bearing R 1 as alkenyl and linear or branched alkyl groups were also checked (Table 3). [6,15] Hoping to fill a gap in the synthetic arsenal, previously reported unreactive azomethine imines 2, bearing R 1 as alkenyl and linear or branched alkyl groups were also checked (Table 3).…”

mentioning

confidence: 99%

“…Very recently reported diastereo-and enantioselective methods provided products 3 bearing R 2 as an alkyl or alkoxy group and R 1 as an aryl or heteroaryl moiety with diastereoselectivities ranging from moderate to excellent. [6,15] Hoping to fill a gap in the synthetic arsenal, previously reported unreactive azomethine imines 2, bearing R 1 as alkenyl and linear or branched alkyl groups were also checked ( Table 3). Pleasingly, the corresponding products 3 q-s were obtained in yields ranging from 49% to 62% and excellent diastereoselectivity.…”

mentioning

confidence: 99%

See 2 more Smart Citations

1,5,7‐Triazabicyclo[4.4.0]dec‐5‐ene (TBD) Triggered Diastereoselective [3+2] Cycloaddition of Azomethine Imines and Pyrazoleamides

et al. 2019

View full text Add to dashboard Cite

A practical and mild approach to prepare tetrahydropyrazolo[1,2-a]-pyrazole-1,7-diones, bearing up to three stereocentres, by reacting ready available N,N'-cyclic azomethine imines and pyrazoleamides under catalytic loading of commercial 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD), has been developed. The products are obtained in good yields and high diastereoselectivity, working at room temperature. Preliminary bioassay showed the products to inhibit growth of Gram-positive bacteria.

show abstract

[3 + 2] Cycloadditions of Azomethine Imines

Grošelj

Svete

2020

Organic Reactions

View full text Add to dashboard Cite

In spite of their late discovery in the middle of 20 th century, the importance of azomethine imines and their [3+2] cycloaddition reactions has grown constantly throughout the decades. Today, [3+2] cycloadditions of azomethine imines have become indispensable in the preparation of pyrazole derivatives with all degrees of saturation. The structural diversity of azomethine imines is wide and comprises acyclic, C , N ‐cyclic, N , N ‐cyclic, and C , N , N ‐cyclic 1,3‐dipoles. Although electron‐deficient dipolarophiles are preferred, electron‐rich dipolarophiles, such as enol ethers and enamines, are also commonly used in these reactions. Compared to cyclocondensation methods and [3+2] cycloadditions with diazoalkanes and nitrile imines, [3+2] cycloadditions with azomethine imines provide access to a greater diversity of pyrazole derivatives with all degrees of saturation. As with other 1,3‐dipolar cycloadditions, a concerted and nearly synchronous mechanism has been proposed for most [3+2] cycloadditions of azomethine imines, although a stepwise mechanism may be viable in some cases. Several examples of asymmetric [3+2] cycloadditions of azomethine imines that afford non‐racemic cycloadducts with high enantioselectivity have been reported. These asymmetric cycloadditions are performed with various types of transition metal catalysts and organocatalysts, and indicate their potential for the asymmetric synthesis of saturated pyrazole derivatives. Finally, many examples of copper‐catalyzed and thermal, strain‐promoted [3+2] cycloadditions of azomethine imines (in particular sydnones) clearly indicate wide applicability of these reactions in bioconjugation, fluorescent labelling, materials functionalization, and other applications outside the realm of pure organic synthesis.

show abstract

Alkaloid-Catalyzed Enantioselective [3 + 2] Cycloaddition of Ketenes and Azomethine Imines

Cited by 33 publications

References 23 publications

Synthesis of Non-Racemic Pyrazolines and Pyrazolidines by [3+2] Cycloadditions of Azomethine Imines

Synthesis of Non-Racemic Pyrazolines and Pyrazolidines by [3+2] Cycloadditions of Azomethine Imines

1,5,7‐Triazabicyclo[4.4.0]dec‐5‐ene (TBD) Triggered Diastereoselective [3+2] Cycloaddition of Azomethine Imines and Pyrazoleamides

[3 + 2] Cycloadditions of Azomethine Imines

Contact Info

Product

Resources

About