2-Phosphaindolizines

Diels–Alder Reactions with the >C=P– Functionality of Annelated Azaphospholes

“…However, just to complete the story recounted in the previous section, general chemical equations showing the use of two methods for the syntheses of these compounds are giv-en in the next section; details of these methods can be found in the relevant research papers cited in our recent reviews. [11][12][13][14] Our comprehensive review entitled 'The Diels-Alder reactions involving >C=P-functionality' 15 includes our results published up to 2008, besides other work in this field. This account covers the literature right from the beginning up to our most recent results.…”

Electron‐Rich Aromatic 1,3‐Heterophospholes – Recent Syntheses and Impact of High Electron Density at σ2P on the Reactivity

“…1,2,4‐Diazaphospholes are similarly stable whereas N ‐bridging heteroaromatic anellated 1,3‐azaphospholes of the 2‐phosphindolizine type are susceptible to hydrolysis with ring opening. Alcohols, NH‐amines, and thiophenols add at the P=C bond of the latter set of compounds after activation by NaOR (ROH) or sulfur oxidation 10a–10c. Non‐anellated aromatic azaphospholes with one P–N bond and one to three N atoms are usually susceptible to addition of ROH and at least in part also to NH‐functional amines, except the lone‐pair donating σ 3 N atom is in the β‐position (conjugation) to σ 2 P. Such reactions have been reviewed in detail previously 9…”

Synthesis of 2‐Phosphaindolizine and [1,3]Azaphospholo[1,5‐a]quin­oline

“…A synthesis starting from N ‐alkylpyridinium salts and PCl 3 involving the intermediacy of a PCl 2 ‐substituted pyridinium ylide was published in 1999 by Bansal et al3 This synthesis demonstrates an impressive predilection for 2‐phosphaindolizine generation. An overview of existing synthetic approaches to, and chemical properties of, 2‐phosphaindolizines inclusive of their 1‐aza, 3‐aza and 1,3‐diaza derivatives has been recently published 4…”