The One-pot Method Is Used For The Synthesis Of Chiral 3,4-2H-1,4-oxazine Derivatives

Oxazine compounds are an important class of organic compounds that have wide applications,such as fluorescent fuels,composite materials,natural products,and antidepressants,receptor antagonists,et.al.Recently,oxazine derivatives have received a great deal of attention,which greatly promoted the development and its further application of.At present stage,there are few reports on the preparation of chiral oxazines from simple starting materials.Therefore,we hope to synthesize oxazine compounds from easily available alkynones through asymmetric hydrogen transfer method and cyclization one-pot multi-step reaction strategy.The first step is to achieve selective reduction of ketones while leaving unreacted alkyne motif.In the second step,we used two different methods to achieve the target product.The first method is the use of bimetallic Ru(II)/Au(I)catalytic system,and the second method is to use Ru(II)/NaH as catalyst.In the second chapter,we mainly introduce the asymmetric hydrogen transfer of alkynones in the presence of the chiral catalyst RuCl[(S,S)-TsDPEN](Mesitylene)as catalyst,and with HCOONa as the hydrogen.In the transfer hydrogenation reaction,a series of chiral alkynol derivatives were synthesized in high yields(up to 96%)with excellent enantioselectivity(up to 98%).Importantly,this protocol could proceeded smoothly under mild reaction conditions.In the third chapter,we mainly introduce two methods to synthesize chiral3,4-2H-1,4-oxazine derivatives.For the first method,we use bimetallic Ru(II)/Au(I)catalystic system to provide 3,4-2H-1,4-oxazine in moderate yields and excellent ee's under mild reaction conditions(40 ~oC in DCE,HCOONa as a hydrogen source).This protocol could eliminate the interaction between the ruthenium complex and gold complex via systematiclly control of the pH.In the second method,under the condition of 40?in DCE,HCOONa was also used as the hydrogen source for asymmetric hydrogen transfer of alkynone.However,we used NaH as cyclization reagent during the transformation from alkynol to 3,4-2H-1,4-oxazine.The advantages of the second lie in its high yields and easy operation.