Trans- 3-PENTEN-2-ONE

Acetyl chloride, reaction with sodium formate, 50, 1 with propylene, aluminum chloride, and quinoline to give trans-3-pentene-2-one,... 

Pentanol, 52, 22 trans-2-Pentenal, 4-hydroxy-4-methyl-, 54, 27 Pent-l-en-3-ol, 52, 22 trans-3-PENTEN-2-ONE, 51, 115 PERBENZOIC ACID, m-CHLORO-,... 

C5H80 trans-3-penten-2-one 3102-33-8 19.543 98.109 1,2 5036 C5H9CI 4-chloro-trans-2-pentene 18610-33-8 16.801 116.874 1,2... 

ANNELATION Dimethyl acetylenedicar-boxylate. Diphenylsulfonium cydoprop-ylide. trans-3-Pentene-2-one. 

Coates and Shaw found that vinylogous amide 11.1 reacts with trans-3-penten-2-one to provide a 91 9 (trans/cis) mixture of diastereomers (Scheme 11) (24). Choice of solvent is critical in formamide, a 50 50 mixture of diastereomers is produced. 

Predict the preferred conformation of the isomeric (cis- and trans ) 3-penten-2-ones, A, R=CH3. How would you expect the conformational picture to change as R becomes progressively larger ... 

Solvents can influence the stereochemical outcome of the Robinson annulation. An interesting example is the one-step annulation using the sodium enolate of 49 to give the octalone 54 and 55. The reaction of the sodium enolate of the 2-methyl-cyclohexanone with trans-3-penten-2-one (53) in the presence of dioxane at room temperature for 100 h gives the cis-4,10-dimethyl-A octal-2-one (54) in 65% yield, while the reaction gives the /ra -isomer 55 in 72% yield in 3 h under same conditions. ... 

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