Methods For Construction Of Aza-heterocycles Based On Acylnitroso Species

In this thesis,we explored the synthetic application of N-acyl nitroso species in the construction of 1-azaspiro[4.4]nonane and 2-azabicyclo[3.3.1]nonane by acylnitroso-ene reaction as well as the preparation of 2-azabicyclo[3.3.1]nonane through acylnitroso-Diels-Alder reaction.During the formal synthesis of cephalotaxine,the acylnitroso-ene reaction was devised as the key reaction to establish the spirocyclic skeleton.After cleavage of the N-O bond,introduction of aryl group and the subquent intramolecular Heck reaction to complete the carbon framework of the Kuehne intermediate.The current approach offers a new synthetic route for the rapid synthesis of cephalotaxine.We designed a convenient route to access the morphan derevitives via acylnitroso-ene cyclization.To clarify the stereochemistry of the corresponding alkene,a substrate bearing a benyl group was prepared.After the careful separation and extensive spectroscopic experiments as well as X-ray analysis,the Z-isomer was identified as the major isomer.It was also found that the oxygen-containing heterocycles was tolerant under the conditons of acylnitroso-ene reaction.To further expore the Diels-Alder cycloaddition of nitroso with diene,several diene substrates were rapidly constructed through Suzuki coupling.The cycloaddition was comlementary to known methods toward marphan skeletons with good tolerance of various functional groups.Based on the primary experiments,it was proposed that the reaction proceeds by pathway rather than a stepwise manner.