Hiroyuki Hisamichi

Cycloadditions in syntheses. Part 41. Chiral spirocyclic 5-arylmethylene-1,3-dioxane-4,6-diones as novel synthons for enantiomerically pure 2-arylcyclopropane-1,1-dicarboxylates☆

Abstract E- and Z-isomers of spirocyclic 5-arylmethylene-1,3-dioxane-4,6-dione, useful synthons for enantiomerically pure cyclopropane-1,1-dicarboxylates, have been synthesized from 1-menthone. Their diastereofacial selectivity is explained by a boat conformation in their dioxanedione ring.

Use of 1,3-dioxin-4-ones and their related compounds in synthesis. XXVII, Novel asymmetric hetero-Diels-Alder reaction using chiral spiro 5-methylene-1,3-dioxane-4,6-diones having 1-menthone at the 2-position

Diastereofacially selective hetero-Diels-Alder reaction of spiro (E or Z)-5-arylidene-1,3-dioxane-4,6-diones and 2-methoxypropene was studied. The dihydropyrans thus obtained were converted to optically active β-arylated δ-oxohexanoic acids. The diastereofacial selectivity of the hetero-Diels-Alder reactions is explained by the sofa-conformation of the heterodienes which accepts the dienophile at the convex α-side preferentially

A facile synthesis of 3-(1,3-butadienyl)cephalosporins

Abstract 3-(1,3-Butadienyl)cephalosporins 1 were prepared in high yields from readily available 3 via phoisphates (E)- 6 .