Study On The Ring Expansion Reaction Of 1-iminylphosphirane

Strained three-membered rings such as cyclopropanes,oxiranes and aziridines have been widely used as key intermediates for the synthesis of medium-sized rings or multiple-ring systems.The metal-mediated cycloaddition reactions of CO with three-membered ring is an effective method for constructing a cyclic ketone skeleton.However,the development of similar chemistry with phosphiranes was somewhat hampered until now by the instability and erratic reactivity of the phosphiranes.It has recently been reported that a 1-acylphosphirane carbonyl tungsten(molybdenum)complex undergoes a phosphorus analogue Cooke-Wilson rearrangement under heating.It was tempting to replace the acyl oxygen by an imino nitrogen and to investigate what will happen with 1-iminylphosphiranesIn the second chapter of this article,the 1-iminylphosphirane carbonyl tungsten(molybdenum)complexes react with alkenes under CO at 130 ? to give original 7-aza-1-phosphanorbornane complexes.The reaction works with electron-rich and electron-poor alkenes.On the basis of DFT calculations,we propose the starting 1-iminylphosphirane complexes rearrange to a dipolar five-membered ring under heating(scheme 2-6).Then,the dipolar ring reacts with alkenes provide the cycloaddition products.In the third chapter of this article,we reported a simple and efficient method to construct peri-fused heterocycles from 1-iminylphosphiranes.A[5+1]mode,which involves the ring-opening of iminylphosphirane,would be of great potential for the construction of six-membered phosphorus carbonyl compounds.And transition metal Mo can be?~2 coordinated with two carbons on the aromatic ring,allowing them to undergo cycloaddition reaction.This dearomatization by metal?~2 coordination has important research prospects in organic synthesis.