Novel Synthetic Method for Piperitenones Through Diels-Alder Reaction

The Diels-Alder adduct obtained from 1-(2-phenyl-selenoethoxy)isoprene and methyl vinyl ketone was applied to synthesis of piperitenones.     

Novel reaction between cyclic formal and ethylene oxide

Novel reactions between trioxane and ethylene oxide were discovered, and three novel cyclic formals were isolated and identified. These novel cyclic compounds clarified the initiation mechanism of the copolymerization of trioxane and ethylene oxide. This type of reaction was not limited to the reaction between trioxane and ethylene oxide but was also generalized to the reaction between the cyclic formal and ethylene oxide. Although an NMR method for analyzing the ethylene oxide sequences of the acetal copolymer from trioxane and ethylene oxide has not yet been established, the three newly found novel cyclic compounds, composed of 1 mol of ethylene oxide and 1 mol of trioxane, 2 mol of ethylene oxide and 1 mol of trioxane, and 3 mol of ethylene oxide and 1 mol of trioxane, were useful for analyzing the ethylene oxide sequences. These compounds gave only one consecutive oxyethylene unit, two consecutive oxyethylene units, and three consecutive oxyethylene units in three consecutive oxymethylene units, respectively, and gave different ¹H NMR spectra for each oxyethylene unit. Considering these data, we synthesized three polymeric model compounds that had one consecutive oxyethylene sequence, two consecutive oxyethylene sequences, and three consecutive oxyethylene sequences in an oxymethylene main chain. By a linear combination of the ¹H NMR spectrum of each oxyethylene unit of the three polymeric model compounds, we succeeded in determining the ethylene oxide sequences by the ¹H NMR method for the copolymer from trioxane and ethylene oxide. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 520–533, 2004     

On the Proper Homotopy Invariance of the Tucker Property

A non-compact polyhedron P is Tucker if, for any compact subset K begong to P, the fundamental group π1 （P - K） is finitely generated. The main result of this note is that a manifold which is proper homotopy equivalent to a Tucker polyhedron is Tucker. We use Poenaru＇s theory of the equivalence relations forced by the singularities of a non-degenerate simplicial map.     

Reaction of tri-n-butyltin formate. III. Synthesis of allylic tri-n-butyltin by the reaction of tri-n-butyltin formate with allylic sulfones and sulfides.

Allylic tri-n-butyltins can be prepared easily by the treatment of allylic sulfones or sulfides with tri-n-butyltin formate in refluxing xylene.