Christo M. Angelov

FIVE-MEMBERED HETEROCYCLIZATION OF PHOSPHORUS-CONTAINING ALLENES BY THEIR REACTION WITH ELECTROPHILES—POSSIBILITIES AND RESTRICTIONS

Abstract In the past several years the reaction ability of phosphorylated allenes with electrophilic reagents has been intensively studied. The experimental data showed that during the interaction of reactants a cyclization of allenic system of π-bonds and phosphorylic group (O[dbnd]P[sbnd]C[dbnd]C[dbnd]C) takes place leading to the formation of P,O-containing heterocyclic compounds. The present paper generalizes the results obtained so far, allowing a critical assessment of the conditions and restrictions for the realization of this interesting reaction.

1,2-ALKADIENEPHOSPHONIC AMIDOESTERS AND THEIR OXAPHOSPHOLIC CYCLIZATION IN REACTION WITH ELECTROPHILIC REAGENTS

Abstract By the reaction of 1,2-alkadienephosphonic dichlorides with dialkylamines and aliphatic alcohols, the 1,2-alkadienephosphonic amidoesters 2a-k have been prepared. The synthesized 1,2-alkadienephosphonates 2a-k have been cyclized in reactions with different electrophiles. The obtained 2,5-dihydro-1,2-oxaphosphole derivatives are characterized by spectral data and elemental analyses.

Di-cyclopentadienyl- und di-indenyl-calcium-komplexe mit ammoniak und tetrahydrofuran

Abstract Dicyclopentadienyl- and diindenyl-calcium and their complexes with twofold coordinated ammonia and tetrahydrofuran are obtained by metalation of cyclopentadiene or indene with calcium or calcium amide in liquid ammonia and subsequent treatment with tetrahydrofuran and heat. IR and 1H NMR spectroscopy are used for structure elucidation. The reactivity of the complexes both in alkylation and in interaction with carbonyl compounds is studied. In this manner alkyl, hydroxyalkyl and alkylidene derivatives of cyclopentadiene and indene axe obtained.

HETEROCYCLIZATION OF 1,2,4- AND 1,3,4-ALKATRIENYLPHOSPHONIC DICHLORIDES WITH ELECTROPHILIC REAGENTS

Abstract By the reaction of 1,2,4- and 1,3,4-alkatrienylphosphonic dichlorides with sulfuryl, sulfenyl and selenenyl chlorides, the different P-containing heterocyclic compounds have been prepared. The obtained heterocycles contained one or two chorine atoms at phosphorus which have great reactivity and can change with another functional groups.

2-Selenophenemethanephosphonic Acid Derivatives-A New Class of Organophosphorus Compounds

Abstract 3-Methyl-2-selenophenemethanephosphonic acid dialkyl esters were obtained by reaction of dialkyl(3-methyl-1,2,4-pentatrienyl)phosphonates with methylselenenyl chlorides.

REACTION OF DIMETHYL ESTERS OF 3-METHYL-1,2-ALKADIENEPHOSPHONIC ACIDS WITH METHYLSULFENYL CHLORIDE—ORIENTATION AND STEREOCHEMISTRY

Abstract The reaction of 3-methyl-1,2-alkadienephosphonic acid (i.e.3-alkyl-3-methylsubstituted allenephosphonic) dimethyl esters 1 with methylsulfenyl chloride 2 is oriented mainly to the 1,2-oxaphosphol-3-ene ring products 3a-d (as diastereoisomeric mixtures when alkyl ≠ CH3). In low extent common 1,2-adducts 4a-d as E,Z-mixtures are also formed. The ratio 3:4 and, in particular the E:Z ratio rises by increase of the size of the alkyl group at the allenic C3-atom of 1. Lowering the temperature of the reaction of 1 and 2 leads to an increase of the annulation stereoselectivity although it remains not very high in the studied temperature interval (−45° – +15°C).

Heterocyclization of 2-(2-chloro-1,3-alkadienyl)-1,3,2-dioxaphospholane 2-oxides in the reaction with sulfenyl chlorides

Abstract The reaction of sulfenyl chlorides with 2-(2-chloro-1,3-alkadienyl)-1,3,2-dioxaphospholane 2-oxides proceeds nonselectively affording five- or six-membered heterocycles depending on the nature of the hydrocarbon moiety in the sulfenyl chloride. The structures of the compounds are determined by NMR and IR spectra.

HETEROCYCLIC PHOSPHONIUM SALTS BY REACTION OF DIMETHYL(1,2-ALKADIENYL)-PHOSPHINE OXIDES WITH ELECTROPHILIC REAGENTS

Abstract Salts of 2,5-dihydro-1,2-oxaphosphole have been prepared by reaction of dimethyl(1,2-alkadienyl)phosphine oxides with halogens, sulfenyl and selenenyl chlorides. The essential influence of tertiary carbenium ions for realization of oxaphospholic cyclization of phosphorylated allenes has been established.

5,6-Dihydro-2H-oxaphosphorine-2-oxides by halogenation of 2-chloro-1,3-alkadienylphosphonic dialkyl esters

Abstract Halogenation of 3- and 4-substituted 2-chloro-1,3-alkadienylphosphonic dialkyl esters leads to the formation of six-membered heterocycles derivatives of 5,6-dihydro-2H-1,2-oxaphosphorine-2-oxides. The structure of the products was established by 1H- and 31P-nmr. In one case column chromatography allowed isolation of two diastereomeric six-membered heterocycles without any evidence of formation of non-cyclic or five-membered cyclic products.

FIVE-MEMBERED PHOSPHORUS HETEROCYCLES BY THE REACTION OF SULFENYL-AND SELENENYL CHLORIDES WITH 2-(1,2-ALKADIENYL)-1,3,2- DIOXAPHOSPHOLANE-2-OXIDES

Abstract It was found that in the reaction of sulfenyl and selenenyl chlorides with 2–(1,2-alkadienyl)-1,3,2-dioxaphospholane-2-oxides cyclization occurred to give 2-oxo-1,2-oxaphosphol-3-ene derivatives. The sulfenyl chlorides with the cyclic esters also afford 1,2-adducts in temperature dependent amounts.