Cyclization of amino alcohols

The cyclizahon of amino alcohols should be an attractive method for the synthesis of N-heterocyclic compounds, mainly because they can be obtained in a single step and without the generation of wasteful byproducts. Carbon-nitrogen bond formation catalyzed by Cp lr complexes has been extended to the synthesis of N-hetero-cyclic compounds by the cyclization of amino alcohols. 

Eary and Clausen reported the cyclizahon of anilino alcohols to give tetrahydro-quinoxalines catalyzed by the I/K2CO3 system [60] the results are summarized in 

Fujita and Yamaguchi et a. reported a new method for the N-heterocyclization of primary amines with diols catalyzed by the l/NaHC03 system, and its application to the asymmetric synthesis of (S)-2-phenylpiperidine [61], The representative results of the reaction of primary amines with diols are summarized in Table 5.11. As shown in entry 1, the reaction of benzylamine with 1,4-butanediol at 110°C for 

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Cyclization of amino alcohol 177 leads to efficient chirality transfer into product dihydropyrrole 178 [126]. 

Cyclization of haloamines 0-46 Cyclization of amino alcohols 0-61 Cyclization of p-azido alcohols 5-31 From 3-iodo azides... 

The asymmetric syntheses of tetrahydroisoquinoline derivatives were also reported. Optically pure 3,4-disubstituted tetrahydroisoquinolines such as 78 were prepared by Friedel-Crafts cyclization of amino alcohols 77 <02TL1885>. Enantioselective syntheses of dihydropyrrolo[2,l-a]isoquinolines via a highly diastereoselective, chiral auxiliary assisted N-acyliminium cyclization was disclosed <02SL593>. The enantioselective synthesis (-)-tejedine, a seco-bisbenzyltetrahydroisoquinoline was also reported. One key step in this synthesis involved a chiral auxiliary-assisted diastereoselective Bischler-Napieralski cyclization <02OL2675>. Additionally, an asymmetric Bischler-Napieralski was reported for the preparation of 1,3,4-trisubstituted 1,2,3,4-tetrahydroisoquinolines <02JCS(P1)116>. 

Reagents formed by combining PhjP with CCU and with diethyl azodicarboxylate (DEAD) promote cyclization of amino alcohols to cyclic amines (Scheme 26). Various 2-amino alcohols reacted with diethoxytriphenylphosphorane (66) to afford the corresponding aziridines in 85-90% yields. The reaction proceeds with retention of the configuration at the amino carbon (C-2) (Scheme 26). In view of... 

Cyclization of amino alcohol 243 leads to efficient chirainy dihydropyrrole 244 [151]. 

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