Efficient and Practical Syntheses of Enantiomerically Pure (S)‐(−)‐Norcryptostyline I, (S)‐(−)‐Norcryptostyline II, (R)‐(+)‐Salsolidine and (S)‐(−)‐Norlaudanosine via a Resolution‐Racemization Method. Issue 10 (29th September 2014)

• Record Type: Journal Article
• Authors: Zhu, Ruiheng; Xu, Zhangli; Ding, Wei; Liu, Shiling; Shi, Xiaoxin; Lu, Xia
• Is Part Of: Chinese journal of chemistry. Volume 32:Issue 10(2014:Oct.)
• Page Start: 1039
• Page End: 1048
• Publication Date: 2014-09-29
• Subjects: Chemistry -- Periodicals; 540.5
• DOI: 10.1002/cjoc.201400471
• Languages: English
• ISSNs: 1001-604X

Abstract

<abstract abstract-type="main" xml:lang="en"> <title>Abstract</title> <p>Four racemic tetrahydroisoquinolines (<italic>RS</italic>)‐(±)‐<bold>1–4</bold> were prepared from homoveratrylamine via amidation, Bischler‐Napieralski reaction and the subsequent reduction. The enantiomerically pure tetrahydroisoquinolines (<italic>S</italic>)‐ (−)‐norcryptostyline I [(<italic>S</italic>)‐(−)‐<bold>1</bold>], (<italic>S</italic>)‐(−)‐norcryptostyline II [(<italic>S</italic>)‐(−)‐<bold>2</bold>], (<italic>R</italic>)‐(+)‐salsolidine [(<italic>R</italic>)‐(+)‐<bold>3</bold>] and (<italic>S</italic>)‐(−)‐norlaudanosine [(<italic>S</italic>)‐(−)‐<bold>4</bold>] were then obtained in 45%, 40%, 41% and 38% yields, respectively, via resolution of the racemic compounds (<italic>RS</italic>)‐(±)‐<bold>1–4 </bold>with half equivalent of chiral acids. In addition, the enantiomerically enriched compounds (<italic>R</italic>)‐(+)‐<bold>1</bold>, (<italic>R</italic>)‐(+)‐<bold>2</bold>, (<italic>S</italic>)‐(−)‐<bold>3</bold> and (<italic>R</italic>)‐(+)‐<bold>4</bold> from the mother liquors were efficiently racemized via a one‐pot redox method in almost quantitative yields.</p> </abstract>