Synthesis of cyclic aminomethylphosphonates and aminomethyl‐arylphosphinic acids by an efficient microwave‐mediated phospha‐mannich approach

Abstract

Microwave‐assisted condensation of 1,3,‐2‐dioxaphosphinane 2‐oxide (1), paraformaldehyde and secondary amines including 5‐ and 6‐membered N‐heterocycles at 55°C gave cyclic aminomethylphosphonates (2), whereas an analogous reaction involving dibenzo[c.e][1,2]oxaphosphinane 2‐oxide (3) resulted in the corresponding aminomethyl‐2‐(2′‐hydroxybiphenyl)phosphinic acids (4) as a consequence of a hydrolytic ring opening following the condensation. © 2008 Wiley Periodicals, Inc. Heteroatom Chem 19:207–210, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20387

Microwave Irradiation as a Useful Tool in Organophosphorus Syntheses

“…A cyclic H-phosphonate, 1,3,2-dioxaphosphorine oxide 2 was also utilized in the phospha-Mannich reactions (Scheme 2). 10 In this case, the use of a solvent prevented the formation of by-products.…”

Environmentally Friendly Chemistry with Organophosphorus Syntheses in Focus

“…It was also found that the syntheses can be carried out without the use of any solvent [27]. Applying heterocyclic amines or >P(O)H species, the α-aminophosphonates and α-aminophosphine oxides synthesized included N-heterocyclic [28] and P-heterocyclic derivatives [29].…”

The Use of MW in Organophosphorus Chemistry

“…1,3,2-dioxaphosphorine oxide) led to N-heterocyclic [73] and P-heterocyclic [74] α-aminophosphonates (51, Y = EtO and 52) and α-aminophosphine oxides (51, Y = Ph) (Schemes 3.36 and 3.37). (53), the heterocyclic ring underwent ring opening by reaction with water formed in the condensation to result in end-product 55 (Scheme 3.38) [74].…”