Advances in Aza-Claisen-Rearrangement-Induced Ring-Expansion Strategies

2017 ◽  
Vol 6 (9) ◽  
pp. 1117-1129 ◽  
Author(s):  
Jong-Wha Jung ◽  
Seok-Ho Kim ◽  
Young-Ger Suh
Keyword(s):  
Claisen Rearrangement ◽  
Ring Expansion ◽  
Expansion Strategies

scholarly journals An unusually rapid Claisen rearrangement involving ring expansion

2000 ◽  
pp. 2339-2340 ◽  
Author(s):  
Gianluca Dimartino ◽  
Jonathan M. Percy
Keyword(s):  
Claisen Rearrangement ◽  
Ring Expansion

scholarly journals A happy medium: the synthesis of medicinally important medium-sized rings via ring expansion

2020 ◽  
Vol 11 (11) ◽  
pp. 2876-2881 ◽  
Author(s):  
Aimee K. Clarke ◽  
William P. Unsworth
Keyword(s):  
Medicinal Chemistry ◽  
Ring Expansion ◽  
Expansion Strategies

Ring expansion strategies are ideally suited to make synthetically challenging, medium-sized rings with much potential in medicinal chemistry.

Ring expansion by tandem double Tebbe–Claisen technology

1992 ◽  
Vol 70 (5) ◽  
pp. 1356-1365 ◽  
Author(s):  
Leo A. Paquette ◽  
Christophe M. G. Philippo ◽  
Nha Huu Vo
Keyword(s):  
Room Temperature ◽  
Claisen Rearrangement ◽  
Ring Expansion ◽  
Carbonyl Groups ◽  
Kinetic Effect ◽  
Slight Excess ◽  
Form Part ◽  
Structural Assembly ◽  
Swern Oxidation ◽  
Neutral Conditions

2-Cyclohexenone rings that form part of a larger structural assembly are amenable to peracid oxidation with formation of an epoxy lactone. These intermediates are readily transformed under acidic, basic, or neutral conditions to ring-contracted aldehydo lactones, which are then subjected to condensation with a slight excess of Tebbe reagent. These conditions result in methylenation of carbonyl groups and set the stage for operation of a Claisen rearrangement. When the latter is catalyzed by Tribal, the sigmatropic process occurs at room temperature. With systems typified by 17 and 24, the isomerization is complete within 15 min. The presence of a proximate angular methyl group as in 9b, 29, and 37 exerts a retarding kinetic effect. In such examples, a period of 6 h is required to achieve completion. Swern oxidation completes the conversion to the 4-cyclooctenones, where the two carbons stemming from the Tebbe reagent are inserted between the original carbonyl and α-olefinic carbons. The overall process is tolerant of ether functionality and additional sites of unsaturation.

ChemInform Abstract: Ring Expansion Reaction of 2-Vinyl-4-methylene-1,3-dioxolanes to 4,5- Dihydro-3(2H)-oxepinones by Claisen Rearrangement.

ChemInform ◽  
2010 ◽  
Vol 25 (37) ◽  
pp. no-no
Author(s):  
J. SUGIYAMA ◽  
K. TANIKAWA ◽  
T. OKADA ◽  
K. NOGUCHI ◽  
M. UEDA ◽  
...  
Keyword(s):  
Claisen Rearrangement ◽  
Ring Expansion ◽  
Ring Expansion Reaction

Ring expansion reaction of 2-vinyl-4-methylene-1,3-dioxolanes to 4,5-dihydro-3(2H)-oxepinones by Claisen rearrangement

1994 ◽  
Vol 35 (19) ◽  
pp. 3111-3114 ◽  
Author(s):  
Jun-ichi Sugiyama ◽  
Kazuki Tanikawa ◽  
Takashi Okada ◽  
Kouichi Noguchi ◽  
Mitsuru Ueda ◽  
...  
Keyword(s):  
Claisen Rearrangement ◽  
Ring Expansion ◽  
Ring Expansion Reaction
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