The reaction of the 4‐phosphorylated allenecarboxylates with different electrophilic reagents such as sulfuryl chloride, bromine, benzenesulfanyl, and benzeneselanyl chlorides takes place with a 5‐endo‐trig cyclization or 2,3‐addition reaction depending on the kind of the substituents in the phosphoryl group. Treatment of the 4‐(dimethoxyphosphopyl)‐allenoates with electrophiles gives a mixture of 2,5‐dihydro‐1,2‐oxaphospholes and furan‐2(5H)‐ones in the ratio of about 1.7:1 as a result of the neighboring group participation of phosphonate and carboxylate groups in the cyclization. On the other hand, (3E)‐4‐(diphenylphosphoryl)‐alk‐3‐enoates were prepared, in moderate yields, by chemo‐, regio, and stereoselective electrophilic addition to the C2C3‐double bond in the allenoate moiety. A possible mechanism involving cyclization and addition reactions of the 4‐phosphorylated allenecarboxylates was proposed.

An efficient method for regioselective synthesis of 4‐heteroatom‐functionalized allenecarboxylates by an atom economical [2,3]‐sigmatropic rearrangement of the mediated 2‐heteroatom‐functionalized alk‐3‐ynecarboxylates is described. Alkyl 4‐(dimethoxyphosphoryl), (diphenylphosphinoyl), (benzenesulfinyl), or (methanesulfonyl)‐alka‐2,3‐dienoates can be readily prepared via reactions of alkyl 2‐hydroxy‐alk‐3‐ynoates with dimethylchlorophosphite, chlorodiphenylphosphine, benzensulfanyl chloride, or methanesulfinyl chloride, respectively, in the presence of a base.

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We have investigated the absorption of the V doped Bi12SiO20 in the spectral region 1.45-2 eV (11 696-16 129 cm-1). The observed absorption bands are due to the V 2+ and V 3+ ions in the same spectral region. These absorption bands do not contain information about the exact energy position of the vanadium levels. Therefore, we have calculated the second derivative of absorption. It is established that all vanadium ions are surrounded by distorted octahedral coordination in Bi12SiO20 (BSO). The energy level structures of the vanadium ions in BSO are also presented. We have calculated the field parameters Dq and the Racah parameters B and C for V 2+ ion. We have determined the field parameters Dq, Ds and Dt for V 3+ ion.