Download PDF
Synlett 2009(6): 886-904  
DOI: 10.1055/s-0028-1088211
ACCOUNT
© Georg Thieme Verlag Stuttgart ˙ New York

Utilization of N,N,N′,N′-Tetramethylfluoroformamidinium Hexafluoro­phosphate (TFFH) in Peptide and Organic Synthesis

Ayman El-Faham*a,b, Sherine N. Khattab*a
a Faculty of Science, Chemistry Department, Alexandria University, P.O. Box 426, Ibrahemia, 21321 Alexandria, Egypt
e-Mail: Aymanel_faham@hotmail.com; e-Mail: ShKh2@Link.net;
b College of Science, King Saud University, P.O. Box 2455, Riyadh, Saudi Arabia
Further Information

Publication History

Received 20 August 2008
Publication Date:
16 March 2009 (online)

    Permissions and Reprints All articles of this category

Abstract

N,N,N′,N′-Tetramethylfluoroformamidinium hexafluoro­phosphate (TFFH) has been shown to be an excellent peptide-coupling reagent. It is an easily handled, crystalline compound, it has a long shelf life, and it reacts rapidly with carboxylic acids to give the corresponding acid fluorides or mixed anhydrides depending on the reaction conditions. TFFH has been shown to be useful as a peptide-coupling reagent and for the preparation of various carboxylic acid derivatives. Both aspects will be surveyed in this Account.

1 Introduction

2 Formation of Carboxylic Acid Halides

3 General Method for the Synthesis of Fluoroformamidinium Salts

4 Solution and Solid-Phase Peptide Coupling Using TFFH

5 Synthesis of Small Phosphotyrosine-Containing Peptides and Peptide Mimetics Incorporating α-Methylated Amino Acids

6 Synthesis of Lysine Analogues

7 Synthesis of Proline Conformation in Tripeptide Fragments of Bovine Pancreatic Ribonuclease A Containing the Nonnatural Proline Analogue 5,5-Dimethylproline

8 Synthesis of Different Types of Dipeptide Building Units Containing N- or C-Terminal Arginine for the Assembly of Backbone Cyclic Peptides

9 Synthesis of Peptidyl Methylcoumarin Esters as Substrates and Active-Site Titrants for Prohormone Processing

10 Synthesis of Boc-(N-All)Xaa-(N-All)Xaa-OMe

11 Synthesis of Alamethicin F30 and Analogues Using TFFH

11.1 C-Terminal Alamethicin F30-Fullerene C60 and C70 Conjugates

11.2 N-Terminal Alamethicin F30-Fullerene C60 Conjugate

12 Miscellaneous Examples

12.1 Synthesis of Isothiocyanates and Hydrazides

12.2 Conversion of Carboxylic Acids into Anilides and Azides

12.3 Acylation of Alcohols, Thiols, and Dithiocarbamates

12.4 Conversion of Carboxylic Acids into Alcohols and Hydroxamic Acids Using TFFH/PTF

12.5 Preparation of 2-Aminobenzimidazole, 2-Aminobenz­oxazole, and 2-Aminobenzothiazole Derivatives

12.6 Formation of Interchain Carboxylic Anhydrides on Self-Assembled Monolayers

12.7 Synthesis of the A1B(A)C Fragment of Everninomicin 13,384-1

12.8 Synthesis of Chiral Polyionic Dendrimers with Complementary Charges

13 Conclusion

Key words

TFFH - amino acid fluorides - solution-phase peptide synthesis - solid-phase peptide synthesis - carboxylic acid derivatives - heterocycles

    References

  • 1a Elmore DT. In Amino Acids, Peptides, and Proteins   Vol. 33:  Barrett GC. Davies JS. The Royal Society of Chemistry; Cambridge: 2002.  p.83 
    Google Scholar
  • 1b Li P. Xu JC. J. Pept. Res.  2001,  58:  129 
    Google Scholar
  • 1c Peptide Chemistry: Design and Synthesis of Peptides, Conformational Analysis and Biological Functions   Hruby VJ. Schwyzer R. Pergamon; Oxford: 1998. 
    Google Scholar
  • 1d Humphrey JM. Chamberlin AR. Chem. Rev.  1997,  97:  2243 
    Google Scholar
  • 1e Carpino LA. Beyermann M. Wenschuh H. Bienert M. Acc. Chem. Res.  1996,  29:  268 
    Google Scholar
  • 1f Bailey PD. An Introduction to Peptide Chemistry   Wiley; Chichester: 1990. 
    Google Scholar
  • 1g Bodanszky M. Principles of Peptide Synthesis   Springer; Berlin: 1984. 
    Google Scholar
  • 1h Klausner YS. Bodanszky M. Synthesis  1972,  453 
    Google Scholar
  • 2 For a review of the work on the use of protected amino acid chlorides, see: Schröder E. Lübke K. The Peptides, Methods of Peptide Synthesis   Vol. 1:  Academic Press; New York: 1965.  p.77 
    Google Scholar
  • 3 Fischer E. Otto E. Ber. Dtsch. Chem. Ges.  1903,  36:  2106 
    CrossrefGoogle Scholar
  • 4 Weisz I. Roboz J. Bekesi G. Tetrahedron Lett.  1996,  37:  563 
    CrossrefGoogle Scholar
  • 5 Rozov LA. Rafalko PW. Evans SM. Brockunier L. Ramig K. J. Org. Chem.  1995,  60:  1319 
    CrossrefGoogle Scholar
  • 6a Zhang L.-H. Chung JC. Costello TD. Valvis I. Ma P. Kauffman S. Ward R. J. Org. Chem.  1997,  62:  2466 
    Google Scholar
  • 6b Lenman MM. Lewis A. Gani D. J. Chem. Soc., Perkin Trans. 1  1997,  2297 
    Google Scholar
  • 6c Carpino LA. Cohen BJ. Stephens KE. Sadat-Aalaee Y. Tien J.-H. Langridge DC. J. Org. Chem.  1986,  51:  3732 
    Google Scholar
  • 7a Senokuchi K. Nakai H. Nagao Y. Sakai Y. Katsube N. Kawamura M. Bioorg. Med. Chem.  1998,  6:  441 
    Google Scholar
  • 7b Wissner A. Grudzinskas CV. J. Org. Chem.  1978,  43:  3972 
    Google Scholar
  • 8 Venkataraman K. Wagle DR. Tetrahedron Lett.  1979,  3037 
    CrossrefGoogle Scholar
  • 9 Kaminski ZJ. Synthesis  1987,  917 
    Article in Thieme ConnectGoogle Scholar
  • 10a Thern B. Rudolph J. Jung G. Tetrahedron Lett.  2002,  43:  5013 
    Google Scholar
  • 10b Falb E. Yechezkel T. Salitra Y. Gilon C. J. Pept. Res.  1999,  53:  507 
    Google Scholar
  • 10c Zouikri M. Vicherat A. Aubry A. Marraud M. Boussard G. J. Pept. Res.  1998,  52:  19 
    Google Scholar
  • 11 Bodanszky M. Principles of Peptides Synthesis   2nd ed.:  Springer-Verlag; Berlin: 1993.  p.11 
    Google Scholar
  • 12a Carpino LA. Sadat-Aalaee D. Chao HG. DeSelms RH. J. Am. Chem. Soc.  1990,  112:  9651 
    Google Scholar
  • 12b Bertho J.-N. Loffet A. Pinel C. Reuther F. Sennyey G. Tetrahedron Lett.  1992,  33:  1303 
    Google Scholar
  • 12c Carpino LA. Mansour EME. Sadat-Aalaee D. J. Org. Chem.  1991,  56:  2611 
    Google Scholar
  • 13a Kim Y.-A. Han S.-Y. Bull. Korean Chem. Soc.  2000,  21:  943 
    Google Scholar
  • 13b Šavrda J. Chertanova L. Wakselman M. Tetrahedron  1994,  50:  5309 
    Google Scholar
  • 13c Carpino LA. Mansour EME. El-Faham A. J. Org. Chem.  1993,  58:  4162(14) 
    Google Scholar
  • 14a Lal GS. Pez GP. Pesaresi RJ. Prozonic FM. Cheng H. J. Org. Chem.  1999,  64:  7048 
    Google Scholar
  • 14b Badu SVV. Gopi HN. Ananda K. Indian J. Chem., Sect. B: Org. Chem. Incl. Med. Chem.  2000,  39:  384 
    Google Scholar
  • 15a Li P. Xu J.-C. Tetrahedron  2000,  56:  8119 
    Google Scholar
  • 15b Li P. Xu JC. Chem. Lett.  2000,  204 
    Google Scholar
  • 16 Mukaiyama T. Tanaka T. Chem. Lett.  1976,  303 
    CrossrefGoogle Scholar
  • 17 Wittmann R. Chem. Ber.  1963,  96:  771 
    CrossrefGoogle Scholar
  • 18 Olah GA. Nojima M. Kerekes I. Synthesis  1973,  487 ; and references cited therein
    Article in Thieme ConnectGoogle Scholar
  • 19a Yarovenko NN. Radsha MA. J. Gen. Chem. USSR (Engl. Transl.)  1959,  29:  2125 
    Google Scholar
  • 19b Olah GA. Nojima M. Kerekes I. J. Am. Chem. Soc.  1974,  96:  925 
    Google Scholar
  • 20 Carpino LA. El-Faham A. J. Am. Chem. Soc.  1995,  117:  4101 
    Google Scholar
  • 21a El-Faham A. Chem. Lett.  1998,  671 
    Google Scholar
  • 21b El-Faham A. Org. Prep. Proced. Int.  1998,  30:  47 
    Google Scholar
  • 21c Akaji K. Kuriyama N. Kiso Y. Tetrahedron Lett.  1994,  35:  3315 
    Google Scholar
  • 22 El-Faham A. Khattab SN. Abdul-Ghani M. Albericio F. Eur. J. Org. Chem.  2006,  1563 
    CrossrefGoogle Scholar
  • 23a Carpino LA. Imazumi H. El-Faham A. Ferrer FJ. Zhang C. Lee Y. Foxman BM. Henklein P. Hanay C. Mugge C. Wenschuh H. Klose J. Beyermann M. Bienert M. Angew. Chem. Int. Ed.  2002,  41:  441 
    Google Scholar
  • 23b Carpino LA. El-Faham A. Minor CA. Albericio F. J. Chem. Soc., Chem. Commun.  1994,  201 
    Google Scholar
  • 24 Carpino LA. J. Am. Chem. Soc.  1993,  115:  4397 
    CrossrefGoogle Scholar
  • 25a Dourtoglu V. Gross B. Lambropoulou V. Zioudrou C. Synthesis  1984,  572 
    Google Scholar
  • 25b Knorr R. Terciak A. Bannworth W. Gillessen D. Tetrahedron Lett.  1989,  30:  1927 
    Google Scholar
  • 26 Fiammengo R. Licini G. Nicotra A. Modena G. Pasquato L. Scrimin P. Broxterman QB. Kaptein B.
    J. Org. Chem.  2001,  66:  5905 
    CrossrefPubMedGoogle Scholar
  • 27 Carpino LA. Ionescu D. El-Faham A. Beyermann M. Henklein P. Hanay C. Wenschuh H. Bienert M. Org. Lett.  2003,  5:  975 
    CrossrefPubMedGoogle Scholar
  • 28 El-Faham A. Kattab SN. Abdul-Ghani M. ARKIVOC  2006,  (xiii):  57 
    Google Scholar
  • 29 Vojkovsky T. Drake B. Org. Prep. Proced. Int.  1997,  29:  497 
    CrossrefGoogle Scholar
  • 30 Bertho J.-N. Loffet A. Pinel C. Reuther F. Sennyey G. Tetrahedron Lett.  1991,  32:  1303 
    CrossrefGoogle Scholar
  • 31 Hudson D. J. Org. Chem.  1988,  53:  617 
    CrossrefGoogle Scholar
  • 32 Izdebski J. Bondaruk J. Gumulka SW. Krzascik P.
    Int. J. Pept. Protein Res.  1989,  33:  77 
    Google Scholar
  • 33 Carey RI. Bordas LW. Slaughter RA. Meadows BC. Wadsworth JL. Huang H. Smith JJ. Furusjo E. J. Pept. Res.  1997,  49:  570 
    Google Scholar
  • 34 For the first solid-phase synthesis of these hindered sequences via isolated amino acid fluorides, see: Wenschuh H. Beyermann M. Krause E. Brudel M. Winter R. Schumann M. Carpino LA. Bienert M. J. Org. Chem.  1994,  59:  3275 
    CrossrefGoogle Scholar
  • 35 Liu WQ. Vidal M. Gresh N. Roques PB. Garbay C. J. Med. Chem.  1999,  42:  3737 
    CrossrefGoogle Scholar
  • 36 Chardin P. Cussac D. Maignan S. Ducruix A. FEBS Lett.  1995,  369:  47 
    CrossrefGoogle Scholar
  • 37 Perich JW. Ruzzene M. Pinna LA. Reynolds EC.
    Int. J. Pept. Protein Res.  1994,  43:  39 
    Google Scholar
  • 38 Williams RM. Im MN. J. Am. Chem. Soc.  1991,  113:  9276 
    CrossrefGoogle Scholar
  • 39 Furet P. Gay B. García-Echeverría C. Rahuel J. Fretz H. Schoepfer J. Caravatti G. J. Med. Chem.  1997,  40:  3551 
    CrossrefGoogle Scholar
  • 40 Weber I. Potier P. Thierry J. Tetrahedron Lett.  1999,  40:  7083 
    CrossrefGoogle Scholar
  • 41 Lenfant M. Wdzieczak-Bakala J. Guittet E. Prome J.-C. Sotty D. Frindel E. Proc. Natl. Acad. Sci. U.S.A.  1989,  86:  779 
    CrossrefGoogle Scholar
  • 42 An SSA. Lester CC. Peng J.-L. Li Y.-J. Rothwarf DM. Welker E. Thannhauser TW. Zhang LS. Tam JP. Scheraga HA. J. Am. Chem. Soc.  1999,  121:  11558 
    CrossrefGoogle Scholar
  • 43 Schumann C. Seyfarth L. Geriner G. Reissmann S.
    J. Pept. Res.  2000,  55:  428 
    CrossrefGoogle Scholar
  • 44 Müller B. Besser D. Kleinwächer P. Arad O. Reissmann S. J. Pept. Res.  1999,  54:  383 
    CrossrefGoogle Scholar
  • 45 Rockwell NC. Krysan DJ. Fuller RS. Anal. Biochem.  2000,  280:  201 
    CrossrefGoogle Scholar
  • 46 Reichwein JF. Liskamp RMJ. Eur. J. Org. Chem.  2000,  2335 
    CrossrefGoogle Scholar
  • 47 Triolo SA. Ionescu D. Wenschuh H. Sole NA. El-Faham A. Carpino LA. Kates SA. In Peptides 1996, Proceedings of the 24th European Peptide Symposium   Ramage R. Epton R. Mayflower Scientific; Kingswinford U.K.: 1998.  p.839-840  
    Google Scholar
  • 48 Wenschuh H. Beyermann M. Haber H. Seydel JK. Krause E. Bienert M. J. Org. Chem.  1995,  60:  405 
    CrossrefGoogle Scholar
  • 49 Schmitt H. Jung G. Liebigs Ann. Chem.  1985,  321 
    CrossrefGoogle Scholar
  • 50 Jung G. Redemann T. Kroll K. Meder S. Hirsch A. Boheim G. J. Pept. Sci.  2003,  9:  784 
    CrossrefGoogle Scholar
  • 51 Redemann T. Jung G. In Situ Fluoride Activation Allows the Preparation of Peptides Not Accessible by Routine Synthesis Protocols, In Peptides 1996, Proceedings of the 24th European Peptide Symposium   Ramage R. Epton R. Mayflower Scientific; Kingswinford U.K.: 1998.  p.749 
    Google Scholar
  • 52 Skiebe A. Hirsch A. J. Chem. Soc., Chem. Commun.  1994,  335 
    CrossrefGoogle Scholar
  • 53 Bayer E. Gfrörer P. Rentel C. Angew. Chem. Int. Ed.  1999,  38:  992 
    CrossrefGoogle Scholar
  • 54 Boas U. Pedersen B. Christensen JB. Synth. Commun.  1998,  28:  1223 
    CrossrefGoogle Scholar
  • 55 Boas U. Gertz H. Christensen JB. Heegaard PMH. Tetrahedron Lett.  2004,  45:  269 
    CrossrefGoogle Scholar
  • 56 Klingsberg E. J. Am. Chem. Soc.  1958,  80:  5786 
    CrossrefGoogle Scholar
  • 57 El-Faham A. Abdul-Ghani M. Org. Prep. Proced. Int.  2003,  35:  369 
    CrossrefGoogle Scholar
  • 58 Pittelkow M. Kamounah FS. Boas U. Pedersen B. Christensen JB. Synthesis  2004,  2485 
    Article in Thieme ConnectGoogle Scholar
  • 59a Albericio F. Chinchilla R. Dodsworth DJ. Nájera C. Org. Prep. Proced. Int.  2001,  33:  203 
    Google Scholar
  • 59b Han SY. Kim YA. Tetrahedron  2004,  60:  2447 
    Google Scholar
  • 59c March J. Advanced Organic Chemistry   4th ed.:  Wiley-Interscience; New York: 1992.  p.904 
    Google Scholar
  • 60 Comprehensive Organic Functional Group Transformations   Vol. 5:  Katritzky AR. Meth-Cohn O. Rees CW. Elsevier; Oxford: 1995.  p.121 
    Google Scholar
  • 61 Greene T. Wuts PGM. Protective Groups in Organic Synthesis   3rd ed.:  Wiley; New York: 1999. 
    Google Scholar
  • 62a Fiesser LF. Fiesser M. Reagents for Organic Synthesis   Vol. 1:  Wiley & Sons; New York: 1967.  p.231 
    Google Scholar
  • 62b Encyclopedia of Reagents for Organic Synthesis   Vol. 3:  Paquette LA. Wiley & Sons; West Sussex: 1995.  p.1751 
    Google Scholar
  • 63 Sheehan LC. Hess GP. J. Am. Chem. Soc.  1955,  77:  1067 
    CrossrefGoogle Scholar
  • 64a Sheehan JC. Henery-Logan KR. J. Am. Chem. Soc.  1957,  79:  1262 
    Google Scholar
  • 64b Nicolaou KC. Sorensen EJ. Classics in Total Synthesis   Vol. 1:  Corey EJ. VCH Publishers; New York: 1996. 
    Google Scholar
  • 65 Holmberg K. Hansen B. Acta Chem. Scand., Ser. B  1979,  33:  410 
    Google Scholar
  • 66a Isobe T. Ishikawa T. J. Org. Chem.  1999,  64:  6984 
    Google Scholar
  • 66b Fujisawa T. Tajima K. Sato T. Bull. Chem. Soc. Jpn.  1983,  56:  3529 
    Google Scholar
  • 66c Fujisawa T. Mori T. Fukumoto K. Sato T. Chem. Lett.  1982,  1891 
    Google Scholar
  • 66d Isobe T. Ishikawa T. J. Org. Chem.  1999,  64:  6989 
    Google Scholar
  • 67a Fujita E. Nagao Y. Seno K. Takao S. Miyasaka T. Kimura M. Watson WH. J. Chem. Soc., Perkin Trans. 1  1981,  914 
    Google Scholar
  • 67b Nagao Y. Kawabata K. Seno K. Fujita E. J. Chem. Soc., Perkin Trans. 1  1980,  2470 
    Google Scholar
  • 68 El-Faham A. Chebbo M. Abdul-Ghani M. Younes G.
    J. Heterocycl. Chem.  2006,  43:  1 
    CrossrefGoogle Scholar
  • 69a del Frenso M. El-Faham A. Carpino LA. Royo M. Albericio F. Org. Lett.  2000,  2:  3539 
    Google Scholar
  • 69b Albericio F. Bofill JM. El-Faham A. Kates SA. J. Org. Chem.  1998,  63:  9678 
    Google Scholar
  • 69c Gausepohl H. Pieles U. Frank RW. In Peptides: Chemistry and Biology, Proceedings of the 12th American Peptide Symposium   Smith JA. Rivier JE. ESCOM; Leiden / The Netherlands: 1992.  p.523 
    Google Scholar
  • 70 Abdul-Ghani M. Khattab SN. El-Massry AM. El-Faham A. Amer A. Org. Prep. Proced. Int.  2004,  36:  121 
    CrossrefGoogle Scholar
  • 71 Douglas EW. Hamilton S. J. Org. Chem.  2002,  67:  7553 
    CrossrefGoogle Scholar
  • 72 Shik Y. Choi IS. Langmuir  2006,  22:  6956 
    CrossrefGoogle Scholar
  • 73 Ulman A. Chem. Rev.  1996,  96:  1533 
    CrossrefPubMedGoogle Scholar
  • 74a Love JC. Estroff LA. Kriebel JK. Nuzzo RG. Whitesides GM. Chem. Rev.  2005,  105:  361 
    Google Scholar
  • 74b Chi YS. Lee JK. Lee KB. Kim DJ. Choi IS. Bull. Korean Chem. Soc.  2005,  26:  361 
    Google Scholar
  • 75 Sullivan TP. Huck WTS. Eur. J. Org. Chem.  2003,  17 
    Google Scholar
  • 76 Chechik V. Crooks RM. Stirling CJM. Adv. Mater.  2000,  12:  1161 
    CrossrefGoogle Scholar
  • 77a Houseman BT. Mrksich M. Angew. Chem. Int. Ed.  1999,  38:  782 
    Google Scholar
  • 77b Templeton AC. Hosteler MJ. Kraft CT. Murray RW. J. Am. Chem. Soc.  1998,  120:  1906 
    Google Scholar
  • 77c Van Ryswyk H. Turtle ED. Watson-Clark R. Tanzer TA. Herman TK. Chong PY. Waller PJ. Taurog AL. Wagner CE. Langmuir  1996,  12:  6143 
    Google Scholar
  • 78a Shimazu K. Teranishi T. Sugihara K. Uosaki K. Chem. Lett.  1998,  669 
    Google Scholar
  • 78b Lee TR. Carey RI. Biebuyck HA. Whitesides GM. Langmuir  1994,  10:  741 
    Google Scholar
  • 78c Bryant MA. Crooks RM. Langmuir  1993,  9:  385 
    Google Scholar
  • 79a Yousaf MN. Chan EWL. Mrksich M. Angew. Chem. Int. Ed.  2000,  39:  1943 
    Google Scholar
  • 79b Gawalt ES. Choi IS. Mrksich M. J. Am. Chem. Soc.  2004,  126:  15613 
    Google Scholar
  • 80 Chi YS. Choi IS. Langmuir  2005,  21:  11765 
    CrossrefGoogle Scholar
  • 81 Olah GA. Nojima M. Kerekes I. Synthesis  1973,  487 
    Article in Thieme ConnectGoogle Scholar
  • 82 Yan L. Marzolin C. Terfort A. Whitesides GM. Langmuir  1997,  13:  6704 
    CrossrefGoogle Scholar
  • 83a Chapman RG. Ostuni E. Yan L. Whitesides GM. Langmuir  2000,  16:  6927 
    Google Scholar
  • 83b Yan L. Huck WTS. Zhao XM. Whitesides GM. Langmuir  1999,  15:  1208 
    Google Scholar
  • 83c Chapman RG. Ostuni E. Liang MN. Meluleni G. Kim E. Yan L. Pier G. Warren S. Whitesides GM. Langmuir  2001,  17:  1225 
    Google Scholar
  • 83d Lee KB. Kim DJ. Yoon KR. Kim Y. Choi IS. Korean J. Chem. Eng.  2003,  20:  956 
    Google Scholar
  • 83e Chi YS. Choi IS. Adv. Funct. Mater.  2006,  16:  1031 
    Google Scholar
  • 84a Nicolaou KC. Mitchell HJ. Suzuki H. Rodríguez RM. Baudoin O. Fylaktakidou KC. Angew. Chem. Int. Ed.  1999,  38:  3334 
    Google Scholar
  • 84b Nicolaou KC. Mitchell HJ. Fylaktakidou KC. Rodríguez RM. Suzuki H. Chem. Eur. J.  2000,  6:  3116 
    Google Scholar
  • 85a Ganguly AK. Pramanik B. Chan TC. Sarre O. Liu YT. Morton J. Girijavallabhan VM. Heterocycles  1989,  28:  83 
    Google Scholar
  • 85b Ganguly AK. In Topics in Antibiotic Chemistry   Vol. 2, Part B:  Sammes PG. Wiley; New York: 1979.  p.61-96  
    Google Scholar
  • 85c Ganguly AK, Girijavallabhan VM, Sarre O, and . inventors; WO  87/02366. 
  • 85d Mahesh P, Gullo VP, Roberta H, Loebenberg D, Morton JB, Miller GH, Kwon HY, and . inventors; EP  0538011A1. 
  • 85e Ganguly AK. McCormick JL. Jinping LA. Saksena K. Das PR. Pradip R. Chan TM. Bioorg. Med. Chem. Lett.  1999,  9:  1209 
    Google Scholar
  • 86 Wright DE. Tetrahedron  1979,  35:  1207 
    CrossrefGoogle Scholar
  • 87a Ganguly AK. McCormick JL. Chan TM. Saksena AK. Das PR. Tetrahedron Lett.  1997,  38:  7989 
    Google Scholar
  • 87b Chan TM. Osterman RM. Morton JB. Ganguly AK. Magn. Reson. Chem.  1997,  35:  529 
    Google Scholar
  • 88 Nicolaou KC. Rodríguez RM. Mitchell HJ. van Delft FL. Angew. Chem. Int. Ed.  1998,  37:  1874 ; Angew. Chem. 1998, 110, 1975
    CrossrefGoogle Scholar
  • 89 Ritzén A. Frejd T. Eur. J. Org. Chem.  2000,  3771 
    CrossrefGoogle Scholar
  • 90 Nicolaou KC. Rodríguez RM. Fylaktakidou KC. Suzuki H. Mitchell HJ. Angew. Chem. Int. Ed.  1999,  38:  3340 
    CrossrefGoogle Scholar
  • 91a Newkome GR. Moorefield CN. Dendric VF. Molecules, Concepts, Synthesis, Perspectives   VCH Publishers; Weinheim: 1996. 
    Google Scholar
  • 91b Engel R. In Advances in Dendritic Macromolecules   Vol. 2:  Newkome GR. JAI Press; Stamford: 1995.  p.73 
    Google Scholar
  • 92 Fischer M. Vogtle F. Angew. Chem. Int. Ed.  1999,  38:  884 
    CrossrefGoogle Scholar