CAS: 107171-75-5; R-(-)-2-Benzylamino-1-Phenylethanol

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2549-14-6 56613-81-1 51096-49-2

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CAS号2549-14-6 (R)-2-氨基-1-苯乙醇

(R)-(-)-2-氯-1-苯乙醇,苄胺 反应 2.0H,以80%的收率获得(R)-(-)-2-苄胺-1-苯乙醇
参考文献:Stereocontrol Between Remote Atom Centers In Acyclic Substrates. Anti Addition Of Hydride To 1,5-,1,6-,And 1,7-Hydroxy Ketones
标题:Stereocontrol Between Remote Atom Centers In Acyclic Substrates. Anti Addition Of Hydride To 1,5-,1,6-,And 1,7-Hydroxy Ketones
摘要:For Conformationally Unconstrained,Acyclic Organic Compounds,The Control Of Stereogenic Centers At Remote Positions Of A Chain,That Is,At A Distance Of Four Or More Atom Centers,Remains A Challenging Problem In Asymmetric Synthesis. We Report On Our Studies Of 1,5,1,6,And 1,7 Diastereoselectivity In Hydride Reductions Of Acyclic Hydroxy Amino Ketones And Related Compounds,Which Were Sparked By Our Discovery Of High 1,5 Diastereocontrol (>10:1) With Substrates Such As 17 And 23. We Have Been Able To Achieve Both High 1,5-And 1,6-Anti Diastereocontrol In The Reduction Of 1,5-And 1,6-Hydroxy Ketone Substrates,Respectively. However,The Level Of 1,7-Anti Diastereocontrol With 1,7-Hydroxy Ketones Was Only Moderate. More Specifically,Reduction Of 23 To 24 With R-Alpine-Hydride Or Zn(Bh4)(2) In Ch2Cl2 (Predominantly) At-78 Degrees C Gave High 1,5-Anti Stereoselectivity (Anti/syn = 10:1 Or 13:1,Respectively),And Reduction Of 34 To 35 With R-Alpine-Hydride (Ch2Cl2) Gave High 1,6-Anti Selectivity (Anti/syn = 12:1,Respectively),Whereas Reduction Of 46 To 44 With R-Alpine-Hydride (Ch2Cl2) Gave Only Moderate 1,7-Anti Stereoselectivity (Anti/syn = 3:1). Results For Reductions Of 1,5-And 1,6-Hydroxy Ketone Substrates Having The N-Benzyl Structural Subunit Replaced (I.E.,27--> 28,29--> 30,31--> 32,52--> 53,54A--> 55A,54B--> 55B,54C--> 55C,And 56--> 57) Clearly Indicate That The Stereoelectronic Character Of This Subunit Plays A Critical. Role In The Attainment Of High Anti Asymmetric Induction. Thus,While We Obtained Exceptionally High 1,6-Anti Stereoselectivity In The Reduction Of The N-Mesitylmethyl Substrate,54C,To 1,6-Diols 55C (Anti/syn = 22:1) With R-Alpine-Hydride At-78 Degrees C In Ch2Cl2,The N-Methyl Substrate,54B,Gave A Relatively Modest Anti/syn Ratio Of 3:1. The Diminished Anti/syn Ratio Of 4:1 In The R-Alpine-Hydride Reduction Of Methoxy Amino Ketone 50 To 51 Also Indicates The Importance Of The Free Hydroxyl Group For Attaining High 1,6-Anti Stereoselectivity. To Rationalize The High Remote Anti Stereocontrol In Such Acyclic Systems,We Discuss A Chelation-Controlled Mechanism,Involving External Hydride Addition To A Bicyclic Metal Complex With A Coordinated Ketone Carbonyl (E.G.,33) Vs Internal Hydride Addition To A Monocyclic Metal Complex With An Uncoordinated Ketone Carbonyl (E.G.,58).
Doi:10.1021/jo981341M