Todd:Catalytic, Asymmetric Pictet-Spengler Reaction

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The Catalytic, Asymmetric Pictet-Spengler Reaction

Matthew H. Todd, School of Chemistry, The University of Sydney, NSW 2006, Australia

(additional authors - add alphabetically if you contribute a scheme+description. Final arbitration on authorship lies with Mat Todd

(This article is a review that acts as background to the open science project to find a catalytic, asymmetric route to praziquantel. The review is open source, meaning anyone can add and edit. When it is deemed to be up to date, error-free and well-written, it will be submitted for publication, but editing can continue here. This page is currently active - when this changes <= these words will be changed (and you can see when the last edit of this page was at the bottom). References for this page may be found in full at the Mendeley page). If you want to get in touch to ask questions please do not use email. You can use the talk page (tab above), or directly insert a question on this page with your initials, or discuss via Google+ pages: Mat, (please add other public places where you can be contacted if you contribute as an author).

Racemic/Achiral

To Do:

• Pictet, A.; Spengler, T. Ber. Dtsch. Chem. Ges. 1911, 44, 2030-2036.
• Tatsui, G. J. Pharm. Soc. Jpn. 1928, 48, 92.
• Cox, E. D.; Cook, J. M. Chem. Rev. 1995, 95, 1797- 1842
• Chrzanowska, M.; Rozwadowska, M. D. Chem. Rev. 2004, 104, 3341-3370.
• Nature: Naoi, M.; Maruyama, W.; Nagy, G. M. Neurotoxicology 2004, 25, 193- 204

Diastereoselective

To Do:

• Cox, E. D.; Hamaker, L. K.; Li, J.; Yu, P.; Czerwinski, K. M.; Deng, L.; Bennett, D. W.; Cook, J. M. J. Org. Chem. 1997, 62, 44-61 and references therein.
• Czarnocki, Z.; MacLean, D. B.; Szarek, W. A. Can. J. Chem. 1986, 64, 2205-2210.
• Czarnocki, Z.; Suh, D.; MacLean, D. B.; Hultin, P. G.; Szarek, W. A. Can. J. Chem. 1992, 70, 1555-1561.
• Czarnocki, Z.; Mieckzkowsi, J. B.; Kiegiel, J.; Arazn ́y, Z. Tetrahyedron: Asymmetry 1995, 6, 2899-2902.
• Waldmann, H.; Schmidt, G.; Henke, H.; Burkard, M. Angew. Chem., Int. Ed. Engl. 1995, 34, 2402-2403.
• Schmidt, G.; Waldmann, H.; Henke, H.; Burkard, M. Chem. Eur. J. 1996, 2, 1566-1571.
• Gremmen, C.; Willemse, B.; Wanner, M. J.; Koomen, G.-J. Org. Lett. 2000, 2, 1955-1958.
• Gremmen, C.; Wanner, M. J.; Koomen, G.-J. Tetrahedron Lett. 2001, 42, 8885-8888.
• Tsuji, R.; Nakagawa, M.; Nishida, A. Tetrahedron: Asymmetry 2003, 14, 177- 180.

Enantioselective

Lewis Acids

To Do:

• Yamada, H.; Kawate, T.; Matsumizu, M.; Nishida, A.; Yamaguchi, K.; Nakagawa, M. J. Org. Chem. 1998, 63, 6348-6354
• Hino, T.; Nakagawa, M. Heterocycles 1998, 49, 499-531.

Bronsted Acids

List reported the first Bronsted acid-catalyzed enantioselective Pictet-Spengler reaction in 2006 (10.1021/ja057444l). Chiral, substituted phosphoric acids were shown to be effective in the PS cyclization of tryptamines with a number of aliphatic and aromatic aldehydes (Scheme List 2006). The diester functionality was found to be necessary, presumably due to promotion of a clean reaction through the Thorpe-Ingold effect (and an aldol side reaction was observed when the esters were absent). Lower yields were typically observed when the methoxy group was absent from the tryptamine aromatic ring.

Scheme (List 2006). Chiral Phosphoric Acid PS Cyclization of Typtamine Diesters

In 2008, Hiemstra reported the preparation of N-benzyl-protected tetrahydro-β-carbolines via an irreversible enantioselective PS reaction of N-benzyltryptamine with various aliphatic and aromatic aldehydes (10.1021/jo8010478). Screening of enantiopure phosphoric acids found reactions catalyzed by the triphenylsilyl substituted acid gave very high conversion (90-100%) and high ee (78-85%). The reaction conditions were optimised by the presence of molecular sieves, possibly due to reduced decomposition of the acid-precursor complex by water. Of the aliphatic aldehydes, no product was observed with the easily enolisable phenylacetaldehyde and low ee (8%) was obtained with 3-phenylpropanal.

Scheme (Hiemstra 2008). Chiral Phosphoric Acid PS Cyclization of N-benzyltryptamines

To Do:
2007 Hiemstra Angew

Early work on addition reactions to aldimines catalyzed by binaphthol-derived chiral phosphoric acids: Akiyama et al ((a) Angew. Chem., Int. Ed. 2004, 43, 1566-1568; (b) Org. Lett. 2005, 7, 2583-2585; (c) Akiyama, T. PCT Int. Appl. WO 200409675, 2004; (d) Adv. Synth. Catal. 2005, 347, 1523-1526. And Terada et al ((a) J. Am. Chem. Soc. 2004, 126, 5356-5357. (b) J. Am. Chem. Soc. 2004, 126, 11804-11805. (c) J. Am. Chem. Soc. 2005, 127, 9360-9361; (d) Terada, M.; Uraguchi, D.; Sorimachi, K.; Shimizu, H. PCT Int. Appl. WO 2005070875, 2005.).

The strengths of these chiral phosphoric acids is governed by:
Akiyama Chem Rev 2007
Terada ChemComm 2008

Organocatalysts

To Do:

• Taylor, M. S.; Jacobsen, E. N. J. Am. Chem. Soc. 2004, 126, 10558- 10559.
  

Iso-Pictet-Spengler (C3 of indole) Jacobsen 2011

Miscellaneous Other Systems/Ones not yet used for PS

Enzymatic examples:
Norcoclaurine synthase Tanner 2007
Strictosidine Synthase [10.1021/ja077190z Stoeckigt 2008]

References

Papers included in the review should be listed here when the description of the science is complete. The papers may be found in full at the Mendeley page)

• Catalytic Asymmetric Pictet-Spengler Reaction, J. Seayad, A. M. Seayad and B. List, J. Am. Chem. Soc. 2006, 128, 1086-1087. Paper