Phosphahydroquinones and oxaphospholes via carbene annulation and cycloaddition reactions of chromium carbonyl carbene complexes and phosphaalkynes

Zwitterionic Organometallates

“…This tendency is consistent with the analogy between the (CO) n MϭC(R')-OR fragment and the ester OϭC(R')O-R fragment, [36] considering the resonance…”

Organophosphorus Compounds, Part 149. Preparation of 1,3-Oxaphospholes by Transition Metal-Catalyzed Reactions of α-Diazo-β-dicarbonyl Compounds with tert-Butylphosphaacetylene

“…2 Currently, only two separate routes to nonbenzo-condensed 1,3-oxaphospholes have been described: Thus, 1,3-oxaphosphole derivatives can be obtained either by reaction of phosphaacetylenes with Fischer-type chromium carbene complexes or by 1,3-dipolar cycloaddition reactions of isomünchnones with the phosphaacetylenes. [3][4][5] Although the reaction of the isomünchnone 5 with the phosphaacetylene 2 furnishes the 1,3-oxophosphole derivative 6 in very good yield in a highly specific reaction, 3,4 the 1,3-oxaphosphole 3 prepared from the carbene complex 1 is isolated in merely 35% yield. 5 The reason for this low yield is the fact that the reaction is not specific for formation of the 1,3-oxaphosphole but is instead accompanied by a side reaction furnishing the phosphaarene species 4.…”

“…[3][4][5] Although the reaction of the isomünchnone 5 with the phosphaacetylene 2 furnishes the 1,3-oxophosphole derivative 6 in very good yield in a highly specific reaction, 3,4 the 1,3-oxaphosphole 3 prepared from the carbene complex 1 is isolated in merely 35% yield. 5 The reason for this low yield is the fact that the reaction is not specific for formation of the 1,3-oxaphosphole but is instead accompanied by a side reaction furnishing the phosphaarene species 4. 5 By use of catalytic amounts of rhodium(II) acetate we have now successfully realized reactions between the cyclic a-diazo-b-dicarbonyl compounds 7 and tert-butylphosphaacetylene 2 at room temperature and thus opened a new access to the class of the 1,3-oxaphospholes.…”

“…5 The reason for this low yield is the fact that the reaction is not specific for formation of the 1,3-oxaphosphole but is instead accompanied by a side reaction furnishing the phosphaarene species 4. 5 By use of catalytic amounts of rhodium(II) acetate we have now successfully realized reactions between the cyclic a-diazo-b-dicarbonyl compounds 7 and tert-butylphosphaacetylene 2 at room temperature and thus opened a new access to the class of the 1,3-oxaphospholes. Previously reported reactions of a-diazocarbonyl compounds with tert-butylphosphaacetylene 2 have always led to the isolation of 1,2,4-diazaphospholes as the final products of a reaction sequence consisting of a 1,3-dipolar cycloaddition with subsequent sigmatropic rearrangement.…”

Fischer-Carbenkomplexe als chemische Multitalente: die unglaubliche Produktpalette ausα,β-ungesättigten Carbenpentacarbonylmetall-Komplexen

“…Tatsächlich wird 3,3-Dimethyl-1-phosphabutin 292 ganz im Sinne einer Dötz-Reaktion an den (1-Naphthyl)carbenchrom-Komplex 291 addiert, [144] wobei in sehr guter Ausbeute das 3-Phosphaphenanthrenderivat 293 entsteht. In einem Konkurrenzexperiment zwischen 292 und 3,3-Dimethylbutin 271 mit dem Komplex 291 reagierte das Phosphaalkin 292 sechsmal so schnell wie das Alkin.…”