New synthesis of royal jelly acid
A new synthesis of (E)-10-hydroxy-2-decenoic acid (royal jelly acid) is described, starting from 8-bromo-1-octanol via condensation of malonic acid with 8-hydroxyoctanal or 8-acetoxyoctanal.
Reactions of phosphines with acetylenes. Part IV. A stable 1,2-diphosphorane. Restricted rotation in a stable alkylidene diphosphorane
The reaction of dimethyl acetylenedicarboxylate with an excess of triphenylphosphine gives a stable 1,2-diphosphorane whose structure [Ph3P:C(CO2Me)·C(CO2Me):PPh3] has been proved by a combination of physical and chemical methods. The n.m.r. spectrum of the diphosphorane at room temperature in deuteriochloroform solution establishes the compound to exist as a mixture of three slowly interconverting conformers, in which there is an energy barrier to rotation about the bond between the ester carbonyl carbon atom and the adjacent carbon atom. Dimethyl acetylenedicarboxylate and diphenylmethylphosphine give an analogous 1,2-diphosphorane with similar properties.
Reaktionen mit Phosphinalkylenen, XIII. Eine Synthese bishomologer Carbonsäuren
Bei der Entschwefelung von Thiolestern 2 mit Raney-Nickel in Gegenwart von Triphenylphosphin-methoxycarbonyl-methylen entstehen α.β-ungesattigte Carbonsaureester. Diese gehen bei der katalytischen Hydrierung oder beim Kochen mit Raney-Nickel in die gesattigten Carbonsaureester uber, deren Kohlenstoffkette um 2 C-Atome gegenuber dem Ausgangsester 2 verlangert ist. Analog lassen sich bei Verwendung von Triphenylphosphin-α-alkoxycarbonylalkyliden 4 α-verzweigte Carbonsaureester 7 aufbauen.