Synthesis Of Chiral Exocyclic Allylic Alcohols And N-aryl Sulfamide Through Hydrogen Transfer Reduction

In recent years,the transfer hydrogenation reaction has developed rapidly.Because of its advantages,it does not require the use of complicated reaction equipment,simple operation,and mild reaction conditions.As present,the application of the hydrogen transfer reduction reaction is mainly focused on the reduction reaction of common functional groups such as ketocarbonyl,alkene,imine and so on,and there are few application examples with special functional groups.The above reaction catalysts generally use chiral phosphorus ligands with complex structure,the price is expensive,and oxygen-sensitive as well as precious metals.Therefore,it is of great significance to find a simple and efficient method to achieve hydrogen transfer reduction.In this paper,we reported the formic acid / triethylamine mixture is used as the hydrogen source to synthesize chiral exocyclic allyl alcohol by asymmetric hydrogen transfer reduction;Metal-free one-pot synthesis of N-arylsulfonamides via B2(OH)4 used to promote water as a hydrogen source.The details are as follows:Series 1: Chemoselective asymmetric transfer hydrogenation of Exo-α,β-unsaturated cycloalkanonecatalyzed by Ruthenium ComplexHydrogen transfer reduction was successfully applied to the synthesis of chiral exocyclic allyl alcohol for the first time,using formic acid / triethylamine(5:2)as the hydrogen source,and using commercially available chiral diamine-derived ruthenium complex as the catalyst under mild conditions,providing the corresponding 48 four-,five-,six-,and seven-membered exocyclic allyl alcoholsin high yield(94%)and withup to 99%ee.The reaction could be performd on the drug loxoprofen and the natural product goniomitine intermediate gram scale,which provided an important reference value for the application of this synthesis method in industrial production.Series 2: Metal-freeone-pot synthesis of N-arylsulfonamideswe have developed a metal-free one-pot two-step synthesis of sulfonamides from readilyavailable nitroarenes was developed.In this procedure,arylamineswere synthesized from inexpensivenitroarenes mediated by B2(OH)4 promote water as a hydrogen sourceand.Use water or a mixture of water as the solvent,and then coupled with sodium arylsulfinates orarylsulfonyl chloridewith iodine as catalyst in aqueous medium under mild conditions.A series of N-arylsulfonamides with 22 functional groups were obtained in moderate to good yields(89%)under the optimal reaction conditions.In addition,this one-pot process is applicable for gram-scale synthesis.