東華大學圖書館 |

Language: English

Help

回圖書館首頁

手機版館藏查詢

Back

Switch To: Labeled | MARC Mode | ISBD

Investigation of the Intramolecular ...

Li, Yixiao,

Linked to FindBook

Google Book

Amazon

博客來

Investigation of the Intramolecular Zwitterionic-1,3-Diaza Claisen Rearrangement to Generate Substituted Cyclic Guanidines via Co(II) Catalyzed Formation of Allylamino-Tethered Carbodiimide /

Record Type:	Electronic resources : Monograph/item
Title/Author:	Investigation of the Intramolecular Zwitterionic-1,3-Diaza Claisen Rearrangement to Generate Substituted Cyclic Guanidines via Co(II) Catalyzed Formation of Allylamino-Tethered Carbodiimide // Yixiao Li.
Author:	Li, Yixiao,
Description:	1 electronic resource (191 pages)
Notes:	Source: Dissertations Abstracts International, Volume: 86-10, Section: B.
Contained By:	Dissertations Abstracts International86-10B.
Subject:	Chemistry. -
Online resource:	https://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=31934127
ISBN:	9798310381520

Investigation of the Intramolecular Zwitterionic-1,3-Diaza Claisen Rearrangement to Generate Substituted Cyclic Guanidines via Co(II) Catalyzed Formation of Allylamino-Tethered Carbodiimide /
Li, Yixiao,

Investigation of the Intramolecular Zwitterionic-1,3-Diaza Claisen Rearrangement to Generate Substituted Cyclic Guanidines via Co(II) Catalyzed Formation of Allylamino-Tethered Carbodiimide /Yixiao Li. - 1 electronic resource (191 pages)

Source: Dissertations Abstracts International, Volume: 86-10, Section: B.

Guanidines are ubiquitous in nature and play pivotal roles in biological, chemical, and industrial applications, occurring in both biomacromolecules and organic materials. Since 2004, the Madalengoitia group has pioneered the development of the 1,3-diaza-Claisen rearrangement, which commences with the desulfurization of electron-deficient thioureas or isothioureas to generate highly electrophilic carbodiimides. These carbodiimides then undergo inter- or intramolecular reactions with tertiary allylic amines to form zwitterionic intermediates, which proceed to guanidines through a [3,3]-sigmatropic rearrangement. However, this protocol exhibits several drawbacks: the mercury or silver salts employed for desulfurization are highly toxic, the method displays limited functional group tolerance, and the inevitably formed triethylammonium triflate byproduct promotes a competing cationic pathway. Additionally, the nucleophilic isothiourea may undergo addition to the carbodiimide, resulting in disproportionation. The intramolecular variant of this rearrangement is facilitated by a cobalt(II)-mediated cross-coupling of allylamino-tethered isocyanides and sulfonyl azides, yielding the electron-deficient carbodiimide intermediate. Intramolecular cyclization of a tertiary amine subsequently furnishes zwitterionic spirocycles, which undergo the 1,3-diaza-Claisen rearrangement to provide guanidines in favorable yields. Substrate scope investigations of sulfonyl azides have demonstrated that reaction efficiency can be enhanced by increasing the electron-withdrawing capacity of the sulfonyl group. Additionally, the rate of rearrangement can be mitigated by incorporating sterically hindered sulfonyl groups. The substrate scope of the tether length and substitution pattern of amino-tethered isocyanide has shown the methodology works optimally with two carbon tethers and tolerates a variety of functionalities. Although three-carbon tethers generate the corresponding zwitterionic intermediates, these intermediates prove unstable and fail to undergo rearrangement. Density functional theory (DFT) calculations are employed to estimate rearrangement activation energies by examining potential transition states, with computational results corroborated by experimental data using zwitterionic intermediates bearing two allyl substituents and diverse alkene-stabilizing fragments. Overall, this new method of carbodiimide generation has resulted in a greener and more efficient methodology to generate allylamino-tethered carbodiimides, and expanded the scope of guanidines that can be generated through the zwitterionic 1,3-diaza-Claisen rearrangement.

English

ISBN: 9798310381520Subjects--Topical Terms:

516420
Chemistry.
Subjects--Index Terms:

Carbodiimides

Investigation of the Intramolecular Zwitterionic-1,3-Diaza Claisen Rearrangement to Generate Substituted Cyclic Guanidines via Co(II) Catalyzed Formation of Allylamino-Tethered Carbodiimide /
LDR:04265nmm a22004213i 4500 001 2434556
005 20250912102041.5
006 m o d
007 cr|nu||||||||
008 261011s2025 miu||||||m |||||||eng d
020 $a 9798310381520
035 $a (MiAaPQD)AAI31934127
035 $a AAI31934127
040 $a MiAaPQD $b eng $c MiAaPQD $e rda
100 1 $a Li, Yixiao, $e author. $3 3824567
245 1 0 $a Investigation of the Intramolecular Zwitterionic-1,3-Diaza Claisen Rearrangement to Generate Substituted Cyclic Guanidines via Co(II) Catalyzed Formation of Allylamino-Tethered Carbodiimide / $c Yixiao Li.
264 1 $a Ann Arbor : $b ProQuest Dissertations & Theses, $c 2025
300 $a 1 electronic resource (191 pages)
336 $a text $b txt $2 rdacontent
337 $a computer $b c $2 rdamedia
338 $a online resource $b cr $2 rdacarrier
500 $a Source: Dissertations Abstracts International, Volume: 86-10, Section: B.
500 $a Advisors: Madalengoitia, Jose S.; White, Matthew Committee members: Brewer, Matthias; Petrucci, Giuesppe.
502 $b Ph.D. $c The University of Vermont and State Agricultural College $d 2025.
520 $a Guanidines are ubiquitous in nature and play pivotal roles in biological, chemical, and industrial applications, occurring in both biomacromolecules and organic materials. Since 2004, the Madalengoitia group has pioneered the development of the 1,3-diaza-Claisen rearrangement, which commences with the desulfurization of electron-deficient thioureas or isothioureas to generate highly electrophilic carbodiimides. These carbodiimides then undergo inter- or intramolecular reactions with tertiary allylic amines to form zwitterionic intermediates, which proceed to guanidines through a [3,3]-sigmatropic rearrangement. However, this protocol exhibits several drawbacks: the mercury or silver salts employed for desulfurization are highly toxic, the method displays limited functional group tolerance, and the inevitably formed triethylammonium triflate byproduct promotes a competing cationic pathway. Additionally, the nucleophilic isothiourea may undergo addition to the carbodiimide, resulting in disproportionation. The intramolecular variant of this rearrangement is facilitated by a cobalt(II)-mediated cross-coupling of allylamino-tethered isocyanides and sulfonyl azides, yielding the electron-deficient carbodiimide intermediate. Intramolecular cyclization of a tertiary amine subsequently furnishes zwitterionic spirocycles, which undergo the 1,3-diaza-Claisen rearrangement to provide guanidines in favorable yields. Substrate scope investigations of sulfonyl azides have demonstrated that reaction efficiency can be enhanced by increasing the electron-withdrawing capacity of the sulfonyl group. Additionally, the rate of rearrangement can be mitigated by incorporating sterically hindered sulfonyl groups. The substrate scope of the tether length and substitution pattern of amino-tethered isocyanide has shown the methodology works optimally with two carbon tethers and tolerates a variety of functionalities. Although three-carbon tethers generate the corresponding zwitterionic intermediates, these intermediates prove unstable and fail to undergo rearrangement. Density functional theory (DFT) calculations are employed to estimate rearrangement activation energies by examining potential transition states, with computational results corroborated by experimental data using zwitterionic intermediates bearing two allyl substituents and diverse alkene-stabilizing fragments. Overall, this new method of carbodiimide generation has resulted in a greener and more efficient methodology to generate allylamino-tethered carbodiimides, and expanded the scope of guanidines that can be generated through the zwitterionic 1,3-diaza-Claisen rearrangement.
546 $a English
590 $a School code: 0243
650 4 $a Chemistry. $3 516420
650 4 $a Organic chemistry. $3 523952
650 4 $a Analytical chemistry. $3 3168300
653 $a Carbodiimides
653 $a Guanidines
653 $a Biomacromolecules
690 $a 0485
690 $a 0490
690 $a 0486
710 2 $a The University of Vermont and State Agricultural College. $b Chemistry. $e degree granting institution. $3 3824568
720 1 $a Madalengoitia, Jose S. $e degree supervisor.
720 1 $a White, Matthew $e degree supervisor.
773 0 $t Dissertations Abstracts International $g 86-10B.
790 $a 0243
791 $a Ph.D.
792 $a 2025
856 4 0 $u https://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=31934127