Ketene Acetals. XIV. The Reactions of Ketene Acetal with Quinones

1944 ◽  
Vol 66 (7) ◽  
pp. 1077-1083 ◽  
Author(s):  
S. M. McElvain ◽  
Edward L. Engelhardt
Keyword(s):  
Ketene Acetal ◽  
Ketene Acetals

Synthèse totale des acides (+) et (–) nonactique à partir de carbohydrates

1981 ◽  
Vol 59 (3) ◽  
pp. 572-583 ◽  
Author(s):  
Robert E. Ireland ◽  
Jean-Paul Vevert
Keyword(s):  
Carbon Atom ◽  
Absolute Configuration ◽  
Claisen Rearrangement ◽  
Sigmatropic Rearrangement ◽  
Chiral Carbon ◽  
Ketene Acetal ◽  
Boat Form ◽  
Aliphatic Esters ◽  
Ketene Acetals

The synthesis of (−) and (+) nonactic acids (2a) and (2b) has been achieved starting from D-mannose (7) and D-gluono-γ-lactone (22) respectively. The key step in the synthesis is the [3,3]-sigmatropic rearrangement of the silylated ketene-acetals IV leading to control of the C-2 configuration of nonactic acid. The ketene-acetals were prepared from aliphatic esters of furanoid-glycals II, which were prepared in ten steps from the carbohydrate precursor. The chiral sites of the glycals arise from the corresponding centres in the starting monosaccharide. This type of ketene-acetal Claisen rearrangement leads to products containing the aldol portion required. At the same time knowledge of the absolute configuration of the chiral carbon atom of nonactic acid allows for the determination of the chair or boat form of the transition state of the [3,3]-sigmatropic rearrangement. [Journal translation]

A comprehensive kinetic study of the conventional free-radical polymerization of seven-membered cyclic ketene acetals

2017 ◽  
Vol 8 (34) ◽  
pp. 5139-5147 ◽  
Author(s):  
Antoine Tardy ◽  
Jean-Claude Honoré ◽  
Didier Siri ◽  
Julien Nicolas ◽  
Didier Gigmes ◽  
...  
Keyword(s):  
Free Radical ◽  
Kinetic Study ◽  
Kinetic Analysis ◽  
Radical Polymerization ◽  
Free Radical Polymerization ◽  
Ketene Acetal ◽  
Cyclic Ketene Acetals ◽  
Ketene Acetals

The current study reports on the kinetic analysis of the free-radical polymerization of several seven-membered cyclic ketene acetal monomers.

Ketene acetals from thermolysis of aryloxy methoxy oxadiazolines. Evidence for carbonyl ylide intermediates

1997 ◽  
Vol 75 (3) ◽  
pp. 326-332 ◽  
Author(s):  
Philippe Couture ◽  
Manal El-Saidi ◽  
John Warkentin
Keyword(s):  
Pure Form ◽  
Second Step ◽  
Carbonyl Ylide ◽  
Ketene Acetal ◽  
Ketene Acetals

Thermolysis of oxadiazolines (5) in benzene at 110 °C leads to ketene acetals (11) as minor products. Carbonyl ylide intermediates (6), and oxiranes (7), presumably in equilibrium with those ylides, are implicated as unstable precursors of the ketene acetals although none of the oxiranes (carbonyl protected α-lactones) were isolable and only one of the ketene acetals was isolable in pure form. The evidence points to the two-step sequence of thermolysis of oxadiazolines, namely, initial cycloreversion to N2 and carbonyl ylide (6), rather than concerted fragmentation to N2, acetone, and carbene (12). The first-formed ylide does fragment to carbene and acetone in a second step that competes with oxirane formation. A tentative mechanism for reaction of 7 with 12, to afford 11, is advanced. Keywords: carbonyl ylide, dioxy oxirane, ketene acetal, oxadiazoline.

Enantioselective Pummerer-type rearrangement by reaction of O-silylated ketene acetal with enantiopure α-substituted sulfoxides

1997 ◽  
pp. 1763-1768 ◽  
Author(s):  
Yasuyuki Kita ◽  
Norio Shibata ◽  
Seiji Fukui ◽  
Masahiko Bando ◽  
Shigekazu Fujita
Keyword(s):  
Ketene Acetal
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