Preparation of anthranils via chemoselective oxidative radical cyclization of 3-(2-azidoaryl) substituted propargyl alcohols

2021 ◽  
Vol 57 (16) ◽  
pp. 2037-2040
Author(s):  
Chao Gao ◽  
Jian Xu ◽  
Shuxian Zhu ◽  
Kaixia Jian ◽  
Qingqing Xuan ◽  
...  
Keyword(s):  
Radical Cyclization ◽  
Radical Cyclizations ◽  
Oxidative Radical Cyclization ◽  
Propargyl Alcohols

In presence of K2S2O8 and HOAc, propargyl alcohols can go oxidative radical cyclizations to give a pool of anthranils. Excellent chemoselectivity was seen, and the synthesized anthranils can be employed as N-nucleophiles in various transformations.

Oxidative radical cyclization to pyrroles under reducing conditions. Reductive desulfonylation of α-sulfonylpyrroles with tri-n-butyltin hydride

1994 ◽  
Vol 72 (1) ◽  
pp. 15-22 ◽  
Author(s):  
Yulia Antonio ◽  
Ma. Elizabeth De La Cruz ◽  
Edvige Galeazzi ◽  
Angel Guzman ◽  
Brian L. Bray ◽  
...  
Keyword(s):  
Radical Addition ◽  
Radical Cyclization ◽  
Radical Cyclizations ◽  
Deuterium Labelling ◽  
Sulfonyl Group ◽  
Reducing Conditions ◽  
Oxidative Radical Cyclization

1-(2-Bromobenzyl)-2-alkanesulfonylpyrroles (1c, 1d) and 1-(4-bromobutyl)-2-methylsulfonfylpyrrols (8) undergo oxidative radical cyclization with partial or complete reductive desulfonylation to the pyrrolizidine derivatives 5 and 9 by an AIBN initiated reaction with tri-n-butyltin hydride. These cyclizations are suggested to proceed via a pseudo SRN1 process involving radical addition to the α position of the pyrrole nucleus not bearing the sulfonyl group. Reductive removal of the alkylsulfonyl moiety is proposed to occur in a second process after completion of the oxidative radical cyclization. The site of the radical addition is supported by deuterium labelling studies. Consistent with the timing of the loss of the sulonyl group is that 2-alkysulfonylpyrroles 11 are reductively desulfonylated under the same conditions that effect the oxidative radical cyclizations.

NO3• Induced Self-Terminating Radical Oxygenations: Diastereoselective Synthesis of Anellated Pyrrolidines

2004 ◽  
Vol 57 (11) ◽  
pp. 1055 ◽  
Author(s):  
Arne Stademann ◽  
Uta Wille
Keyword(s):  
Nitrogen Atom ◽  
Radical Cyclization ◽  
Radical Cyclizations ◽  
Diastereoselective Synthesis ◽  
Reaction Sequence ◽  
Complex Interplay ◽  
Pyrrolidine Ring ◽  
Substitution Pattern ◽  
Nitrate Radicals ◽  
Oxidative Radical Cyclization

Anellated pyrrolidines 19–22 were obtained through a diastereoselective self-terminating, oxidative radical cyclization cascade by treating the cis-cyclopentyl substituted alkynyl amines 14–18 with photochemically generated nitrate radicals, NO3●. A fast and modular access to the starting materials 14–18 was developed, which readily enables variation of the substitution pattern at the pyrrolidine ring formed upon radical cyclization. The diastereoselectivity of this reaction sequence was found to be strongly influenced by the nature of the substituents at the nitrogen atom. This shows that a complex interplay of both steric and stereoelectronic effects orchestrates the stereoselectivity of 5-exo radical cyclizations of highly substituted radicals.

scholarly journals Activation modes in biocatalytic radical cyclization reactions

2021 ◽  
Author(s):  
Yuxuan Ye ◽  
Haigen Fu ◽  
Todd K Hyster
Keyword(s):  
Heme Iron ◽  
Radical Cyclization ◽  
Cytochrome P450 Monooxygenases ◽  
Radical Cyclizations ◽  
Cyclization Reactions ◽  
Complex Molecules ◽  
P450 Monooxygenases ◽  
Non Heme Iron ◽  
Essential Reactions ◽  
Isopenicillin N

Abstract Radical cyclizations are essential reactions in the biosynthesis of secondary metabolites and the chemical synthesis of societally valuable molecules. In this review, we highlight the general mechanisms utilized in biocatalytic radical cyclizations. We specifically highlight cytochrome P450 monooxygenases (P450s) involved in the biosynthesis of mycocyclosin and vancomycin, non-heme iron- and α-ketoglutarate-dependent dioxygenases (Fe/αKGDs) used in the biosynthesis of kainic acid, scopolamine, and isopenicillin N, and radical S-adenosylmethionine (SAM) enzymes that facilitate the biosynthesis of oxetanocin A, menaquinone, and F420. Beyond natural mechanisms, we also examine repurposed flavin-dependent ‘ene’-reductases (ERED) for non-natural radical cyclization. Overall, these general mechanisms underscore the opportunity for enzymes to augment and enhance the synthesis of complex molecules using radical mechanisms.

Tandem Radical Cyclizations: a One-Step Synthesis of Stereoisomeric Tricyclo[6.3.0.02,6]undecanes From Acyclic Precursors

1995 ◽  
Vol 48 (2) ◽  
pp. 261 ◽  
Author(s):  
DP Curran ◽  
SN Sun
Keyword(s):  
Radical Cyclization ◽  
Radical Cyclizations ◽  
Low Concentration ◽  
One Step

Radical cyclization of (1E,5Z)-1-iodoundeca-1,5,10-triene with triphenyltin hydride provides one acyclic, one monocyclic, two bicyclic and four tricyclic products. At low concentration (0.002 M), the title tricycloundecane products resulting from triple cyclization predominate, but the stereoselectivity is low. Cyclization of (1E,5Z)-1-iodo-8,8-bis( phenylsulfonyl )undeca-1,5,10-triene followed by reductive desulfonylation provides a similar ratio of products to the parent. The results show that this class of triple cyclization occurs well, but the level of stereoselectivity must be raised for it to become synthetically useful.

Oxidative Radical Cyclization on Enamide Systems Using n-Bu3SnH and Dilauroyl Peroxide.

ChemInform ◽  
2003 ◽  
Vol 34 (44) ◽  
Author(s):  
Miguel A. Guerrero ◽  
Raymundo Cruz-Almanza ◽  
Luis D. Miranda
Keyword(s):  
Radical Cyclization ◽  
Oxidative Radical Cyclization

ChemInform Abstract: Oxidative Radical Cyclization to Pyrroles Under Reducing Conditions. Reductive Desulfonylation of α-Sulfonylpyrroles with Tri-n- butyltin Hydride.

ChemInform ◽  
2010 ◽  
Vol 25 (37) ◽  
pp. no-no
Author(s):  
Y. ANTONIO ◽  
MA. E. DE LA CRUZ ◽  
E. GALEAZZI ◽  
A. GUZMAN ◽  
B. L. BRAY ◽  
...  
Keyword(s):  
Radical Cyclization ◽  
Reducing Conditions ◽  
Oxidative Radical Cyclization

Synthesis of Benzannulated Spiroketals Using an Oxidative Radical Cyclization

Synthesis ◽  
2011 ◽  
Vol 2011 (09) ◽  
pp. 1383-1398 ◽  
Author(s):  
Margaret Brimble ◽  
Jonathan Sperry ◽  
Yen-Cheng Liu ◽  
Zoe Wilson ◽  
Jonathan Hubert
Keyword(s):  
Radical Cyclization ◽  
Oxidative Radical Cyclization

One-pot synthesis of cyclophane-type macrocycles using manganese(iii)-mediated oxidative radical cyclization

2011 ◽  
Vol 9 (5) ◽  
pp. 1491 ◽  
Author(s):  
Yosuke Ito ◽  
Yuichi Tomiyasu ◽  
Takahiro Kawanabe ◽  
Keisuke Uemura ◽  
Yuu Ushimizu ◽  
...  
Keyword(s):  
Radical Cyclization ◽  
One Pot ◽  
One Pot Synthesis ◽  
Oxidative Radical Cyclization
Sign in / Sign up

Export Citation Format

Share Document