[4+2]‐Cycloadditionen von Phosphinodiazoalkanen: Synthese von 1,2,4λ⁵‐Diazaphosphininen

Abstract

Zu Partnern für [4 + 2]‐Cycloadditionen werden Diazoalkane durch einen Phosphinosubstituenten am Diazokohlenstoffatom. Dies zeigen die Umsetzungen von 1, R = OMe, Ph, mit 2, R′ = OMe, Ph, zu den Diaza‐λ5‐phosphininen 3. Mit tBuCP dagegen reagieren die Diazoverbindungen 1 in „normaler”︁ [3 + 2]‐Cycloaddition.

Diphosphanylketenimines: New Reagents for the Synthesis of Unique Phosphorus Heterocycles

“…The diphosphanylketenimine (PPh 2 ) 2 CCNPh ( 3 ) and its mono‐oxidized form (OPPh 2 )(PPh 2 )CCNPh ( 8 ) behave as 1,3‐dipoles towards a variety of dipolarophiles such as alkynes, isocyanates and isothiocyanates, through formal [3+2] and [3+3] cycloaddition reactions involving the phosphanyl residues, allowing the synthesis of remarkable five‐ and six‐membered phosphaheterocycles. Thus, it can be concluded that the presence of the phosphanyl substituents considerably modify the reactivity of 3 and 8 when compared with classical organic ketenimines, in agreement with that already observed by Regitz et al4 and Bertrand et al1 for other phosphanyl substituted organic functionalities.…”

“…In line with all of the above, and with other reported cycloaddition reactions of alkynes with phosphanyl‐substituted dipoles,1, 4, 12, 13 a mechanism for the formation of 5 a , b is proposed in Scheme . First, nucleophilic attack of a phosphorus atom of 3 at the electron‐poor alkyne followed by a 1,5‐electrocyclization affords 4a , b .…”

“…The reactivity of organic functional groups in cycloaddition reactions can be considerably enlarged by introducing phosphanyl substituents in the corresponding organic molecules, since the phosphorus atoms of the phosphanyl groups are frequently involved in the annelation processes. This is exemplified by a series of reactions of the electron‐poor alkyne dimethyl acetylenedicarboxylate with phosphanyl‐substituted carbodiimides,1 azides,2 nitrilimines3 and diazoderivatives,4 which afford a variety of new phosphorus containing heterocycles, such as 1,2 λ 5 ‐azaphosphole, 1,2 λ 5 ‐azaphosphete, 1,2,4,3 λ 5 ‐triazaphosphinine and 1,2,4 λ 5 ‐diazaphosphinine derivatives, respectively.…”

Phosphaalkine

“…B. die Chlordiazirine (31) in uberschussigem Phosphaalkin (4). so findet [2+ 1)-Cycloaddition der thermisch erzeugten Carbenc an die P/C-Dreifachbindung zu den I-Phosphirenen (33) aktion, bei der sich der Ubergang von h'din k7a"-Phosphor durch eine markante Hochfeldverschiebung (6 = +315 bzw.…”