Pictet-Spengler isoquinoline

The Pictet-Spengler reaction has been carried out on various solid support materials " and with microwave irradiation activation.Diverse structural analogues of (-)-Saframycin A have been prepared by carrying out the Pictet-Spengler isoquinoline synthesis on substrates attached to a polystyrene support. Amine 20 was condensed with aldehyde 21 followed by cyclization to give predominantly the cis isomer tetrahydroisoquinoline 22 which was further elaborated to (-)-Saframycin A analogues. 

Tinsley, J. M. Pictet-Spengler Isoquinoline Synthesis In Name Reactions in Heterocyclic Chemistry, Li, J. J. Corey, E. J., Eds. Wiley Sons Hoboken, NJ, 2005, 469 79. (Review). 

PICTET-SPENGLER ISOQUINOLINE SYNTHESIS Diisobutylaluminum hydride. 

Pictet-Spengler isoquinoline synthesis. The final steps in a synthesis of (—)-antirhine (2), a Corynanthe-type indole alkaloid, involved partial reduction of the lactam 1 to a hemiamina), which cyclizes to 2 in the presence of dilute HC1,2... 

PICTET - SPENGLER Isoquinoline synthesis 299 PILLOTY - ROBINSON Indole synthsta 300 PINNER Imno ethers synthesa 300 PInacd 178... 

Another useful variation is the Pictet-Spengler isoquinoline synthesis, also known as the Pictet-Spengler reaction. The reactive intermediate is an iminium ion 49 rather than an oxygen-stabilized cation, but attack at the electrophilic carbon of the C=N unit (see 16-31) leads to an isoquinoline derivative. When a p-aryla-mine reacts with an aldehyde, the product is an iminium salt, which cyclizes with an aromatic ring to complete the reaction and generate a tetrahydroisoquinoline." ° A variety of aldehydes can be used, and substitution on the aromatic ring leads to many derivatives. When the reaction is done in the presence of a chiral thiourea catalyst, good enantioselectivity was observed." ... 

PICTET-SPENGLER Isoquinoline Synthesis Isoquinoline synthesis of phenethylamine and pyruvic acid derivatives (see 1st edition). 

Another classical approach is the Pictet-Spengler isoquinoline synthesis. 66c x is variation generates an iminium salt from an amine and an aldehyde (a Schiff base), which cyclizes with an aromatic ring to complete the reaction. A synthetic example is taken from Liang s synthesis of chrysotricine.1 2 xhg reaction of amine 279 with aldehyde 280, in the presence of trifluoroacetic acid, initially gave an iminium salt (281). Subsequent Friedel-Crafts cyclization of the iminium salt gave the isoquinoline product (282 in 70% yield). The amino groups of amino acid derivatives also serve as excellent partners in this reaction.1 3... 

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