Efficient One‐Pot Synthesis of Secondary Cyclic Phosphanes with Easy Regeneration of the Phosphorus‐Donor Reagent Used

Abstract

Phosphanes: No pain, all gain. A regenerable phosphorus donor is the key to an efficient and economic one‐pot synthesis of five‐ and six‐membered secondary cyclic phosphanes. The reaction, at room temperature, of 1 with 1 equivalent of bis(Grignard reagent) 2 followed by treatment with aqueous acid gives cyclic phosphanes 3 in 70–80 % yield and the new compound 4. Simply treating 4 with PCl3 quantitatively regenerates the starting reagent 1, which can be reused without further purification.

General and Efficient One‐Pot Synthesis of Tertiary Phosphane–Borane Complexes Containing Different Alkyl Groups and In Situ Facile Recycling of the Phosphorus Donor Reagent

“…The simple treatment of 3 with PCl 3 quantitatively and immediately regenerated the starting reagent 1, which can be reused without further purification (Scheme 1). [24] The intermediate involved in the synthesis of the phosphanes 2 from 1 might be a hypervalent phosphorus species such as A, as reported elsewhere. [25] We also reported a new efficient method for the synthesis of borane complexes 4 (70-85 % yield) of the secondary phosphanes 2 by simple treatment of the reaction mixture with acetic acid followed by the in situ addition of the BH 3 ·THF complex.…”

“…The reformed reagent 1 was almost quantitatively separated from the reaction mixture by simple crystallization, [30] whereas the phosphane-borane complex, present in the mother liquor, was purified by chromatography. Compared with the previous procedure [24] for the recycling of compound 1, which involved treatment of the reaction mixture containing the magnesium salt of 3 with acidic water followed by the isolation of 3, this new in situ recycling process is very easy and fast. The procedure reported here is made possible by the chemical stability of tertiary phosphane-borane complexes in the presence of PCl 3 , which can be added directly to the reaction mixture.…”

Transformations of benzothiadiphosphole system: General one‐pot synthesis of 1,2,5‐dithiaphosphepines and their precursor phosphanethiols

“…More recently [7], we have reported a very efficient and economic new method SCHEME 1 for the one-pot preparation of secondary cyclic phosphanes 5 (n = 1, 2) in 70-80% yields. This method consists in the treatment at room temperature of reagent 1 with one equivalent of bis-Grignard 2.…”

Phosphines and Related Tervalent Phosphorus Systems

“…The biproduct (134) can also be isolated cleanly from the aqueous phase in 90% yield, and recycled back to (132) by treatment with phosphorus trichloride. 305 The established ring-opening of aziridines on treatment with diphenylphosphine has been used to prepare further examples of chiral b-aminophosphines. 306 The regiospecificity of the reaction of diphenylchlorophosphine with enamines derived from b-aminocrotonic acid has been studied, providing routes to enamino-vinyl-and -allyl-phosphines.…”

“…The crystal structure of a lithium salt of (304, R¼Me) has been determined, and theoretical studies suggest that the negative charge is largely localised on the a-carbons. 872 Treatment of related anions with hexachloroethane, followed by gallium trichloride, has given the 1-methylphosphinium salts (305), which readily add nucleophiles to form l 5 -phosphinines. 873 The coordination chemistry of phosphahexadienyl anions has also attracted interest.…”