Synthesis 2013; 45(9): 1121-1159
DOI: 10.1055/s-0032-1316869
review
© Georg Thieme Verlag Stuttgart · New York

Claisen Rearrangement of Aliphatic Allyl Vinyl Ethers from 1912 to 2012: 100 Years of Electrophilic Catalysis

Julia Rehbein
a   Fachbereich Chemie, Institut für Organische Chemie, Universität Hamburg, 20146 Hamburg, Germany
,
Martin Hiersemann*
b   Fakultät Chemie, Technische Universität Dortmund, 44227 Dortmund, Germany   Email: martin.hiersemann@udo.edu
› Author Affiliations
Further Information

Publication History

Received: 06 January 2013

Accepted after revision: 12 February 2013

Publication Date:
17 April 2013 (online)


Abstract

This review summarizes, from a personal perspective, the development of catalytic asymmetric Claisen rearrangements from 1912 to 2012.

1 Introduction

2 Gosteli–Claisen Rearrangement

3 Claisen Rearrangement Using Stable Enols: Kojic Acid and Diosphenols

4 The Early Years: Catalysis by Brønsted Acids

5 Lewis Acid Mediated Claisen Rearrangements: The Aluminum Age

6 Catalysis by Precious Metals

7 Catalysis by σ-Lewis Acids

8 Catalysis by Achiral Organocatalysts

9 Catalytic Asymmetric Claisen Rearrangements

10 Conclusion

 
  • References

  • 1 Claisen L. Chem. Ber. 1912; 45: 3157
  • 2 Schuler FW, Murphy GW. J. Am. Chem. Soc. 1950; 72: 3155
  • 3 Stein L, Murphy GW. J. Am. Chem. Soc. 1952; 74: 1041
  • 4 Lauer WM, Kilburn EI. J. Am. Chem. Soc. 1937; 59: 2586
  • 5 Ralls JW, Lundin RE, Bailey GF. J. Org. Chem. 1963; 28: 3521
  • 6 Wiest O, Houk KN. J. Org. Chem. 1994; 59: 7582
  • 7 Meyer MP, DelMonte AJ, Singleton DA. J. Am. Chem. Soc. 1999; 121: 10865
  • 8 Dewar MJ. S, Healy EF. J. Am. Chem. Soc. 1984; 106: 7127
  • 9 Vance RL, Rondan NG, Houk KN, Jensen F, Borden WT, Komornicki A, Wimmer E. J. Am. Chem. Soc. 1988; 110: 2314
  • 10 Dewar MJ. S, Jie C. J. Am. Chem. Soc. 1989; 111: 511
  • 11 Wiest O, Black KA, Houk KN. J. Am. Chem. Soc. 1994; 116: 103367
  • 12 Yoo HY, Houk KN. J. Am. Chem. Soc. 1994; 116: 12047
  • 13 Carpenter BK. Tetrahedron 1978; 34: 1877
  • 14 Burrows CJ, Carpenter BK. J. Am. Chem. Soc. 1981; 103: 6984
  • 15 Gajewski JJ, Conrad ND. J. Am. Chem. Soc. 1979; 101: 6693
  • 16 Gajewski JJ, Gee KR, Jurayj J. J. Org. Chem. 1990; 55: 1813
  • 17 Gajewski JJ, Brichford NL. J. Am. Chem. Soc. 1994; 116: 3165
  • 18 Gajewski JJ. Acc. Chem. Res. 1997; 30: 219
  • 19 Hurd CD, Pollack A. J. Org. Chem. 1939; 3: 550
  • 20 Coates RM, Rogers BD, Hobbs SJ, Curran DP, Peck DR. J. Am. Chem. Soc. 1987; 109: 1160
  • 21 Grieco PA, Brandes EB, McCann S, Clark JD. J. Org. Chem. 1989; 54: 5849
  • 22 Cramer CJ, Truhlar DG. J. Am. Chem. Soc. 1992; 114: 8794
  • 23 White WN, Wolfarth EF. J. Org. Chem. 1970; 35: 2196
  • 24 Brandes EB, Grieco PA, Gajewski JJ. J. Org. Chem. 1989; 54: 515
  • 25 Severance DL, Jorgensen WL. J. Am. Chem. Soc. 1992; 114: 10966
  • 26 Sehgal A, Shao L, Gao J. J. Am. Chem. Soc. 1995; 117: 11337
  • 27 For a review, see: Ziegler FE. Chem. Rev. 1988; 88: 1423
  • 28 Hilvert D, Nared KD. J. Am. Chem. Soc. 1988; 110: 5593
  • 29 Hilvert D, Carpenter SH, Nared KD, Auditor M.-T. Proc. Natl. Acad. Sci.U.S.A. 1988; 85: 4953
  • 30 Jackson DY, Jacobs JW, Sugasawara R, Reich SH, Bartlett PA, Schultz PG. J. Am. Chem. Soc. 1988; 110: 4841
  • 31 Davidson MM, Hillier IH, Vincent MA. Chem. Phys. Lett. 1995; 246: 536
  • 32 Rehbein J, Hiersemann M. J. Org. Chem. 2009; 74: 4336
  • 33 Khaledy MM, Kalani MY. S, Khuong KS, Houk KN, Aviyente V, Neier R, Soldermann N, Velker J. J. Org. Chem. 2003; 68: 572
  • 34 Zhang Y.-D, Ren W.-W, Lan Y, Xiao Q, Wang K, Xu J, Chen J.-H, Yang Z. Org. Lett. 2008; 10: 665
  • 35 Ozturk C, Aviyente V, Houk KN. J. Org. Chem. 2005; 70: 7028
  • 36 Gajewski J, Conrad N. J. Am. Chem. Soc. 1979; 101: 2747
  • 37 Kupczyk-Subotkowska L, Saunders WH. Jr, Shine HJ, Subotkowski W. J. Am. Chem. Soc. 1993; 115: 5957
  • 38 Singleton DA, Thomas AA. J. Am. Chem. Soc. 1995; 117: 9357
  • 39 The construction of the vinyl ether double bond, particularly in a configurationally defined way, constitutes a challenge in its own right. For a recent review on the synthesis of vinyl ethers, see: Winternheimer DJ, Shade RE, Merlic CA. Synthesis 2010; 2497
  • 40 Burgstahler AW. J. Am. Chem. Soc. 1960; 82: 4681
  • 41 Burgstahler AW, Nordin IC. J. Am. Chem. Soc. 1961; 83: 198
  • 42 See also: Hill RK, Edwards AG. Tetrahedron Lett. 1964; 5: 3239
  • 43 For 1,3-chirality transfer in the aromatic Claisen rearrangement, see: Alexander ER, Kluiber RW. J. Am. Chem. Soc. 1951; 73: 4304
  • 44 See reference 2 in: Hill RK, Chan T.-H. J. Am. Chem. Soc. 1966; 88: 866
  • 45 von E Doering W, Roth WR. Tetrahedron 1962; 18: 67
  • 46 Vittorelli P, Winkler T, Hansen H.-J, Schmid H. Helv. Chim. Acta 1968; 51: 1457
  • 47 Hansen H.-J, Schmid H. Tetrahedron 1974; 30: 1959
  • 48 Brannock KC. J. Am. Chem. Soc. 1959; 81: 3379
  • 49 Stork G, Raucher S. J. Am. Chem. Soc. 1976; 98: 1583
  • 50 Martinez GR, Grieco PA, Williams E, Kanai K, Srinivasan CV. J. Am. Chem. Soc. 1982; 104: 1436
  • 51 Ireland RE, Varney MD. J. Am. Chem. Soc. 1984; 106: 3668
  • 52 Lythgoe B, Metcalfe DA. Tetrahedron Lett. 1975; 16: 2447
  • 53 See also: Bartlett PA, Pizzo CF. J. Org. Chem. 1981; 46: 3896
  • 54 Abelman MM, Funk RL, Munger JD. J. Am. Chem. Soc. 1982; 104: 4030
  • 55 Cameron AG, Knight DW. Tetrahedron Lett. 1982; 23: 5455
  • 56 Boeckman RK, Shair MD, Vargas JR, Stolz LA. J. Org. Chem. 1993; 58: 1295
    • 57a Hurd CD, Pollack MA. J. Am. Chem. Soc. 1938; 60: 1905
    • 57b The qualitative results of Hurd and Pollack were later quantified by Murphy, see references 2 and 3.
  • 58 Burrows CJ, Carpenter BK. J. Am. Chem. Soc. 1981; 103: 6983
  • 59 Curran DP, Suh YG. J. Am. Chem. Soc. 1984; 106: 5002
  • 60 Wilcox CS, Babston RE. J. Am. Chem. Soc. 1986; 108: 6636
  • 61 Gao J. J. Am. Chem. Soc. 1994; 116: 1563
  • 62 Hu H, Kobrak MN, Xu C, Hammes-Schiffer S. J. Phys. Chem. A 2000; 104: 8058
  • 63 Higashi M, Hayashi S, Kato S. J. Chem. Phys. 2007; 126: 144503
  • 64 Barnes RP, Chigbo FE. J. Org. Chem. 1963; 28: 1644
  • 65 Gosteli J. Helv. Chim. Acta 1972; 55: 451
  • 66 Hase TA, Ourila A, Holmberg C. J. Org. Chem. 1981; 46: 3137
  • 67 Berryhill SR, Price T, Rosenblum M. J. Org. Chem. 1983; 48: 158
  • 68 Gajewski JJ, Jurayj J, Kimbrough DR, Gande ME, Ganem B, Carpenter BK. J. Am. Chem. Soc. 1987; 109: 1170
  • 69 Kupczyk-Subotkowska L, Saunders WH. Jr, Shine HJ, Subotkowski W. J. Am. Chem. Soc. 1994; 116: 7088
  • 70 Shi G.-q, Cao Z.-y, Cai W.-l. Tetrahedron 1995; 51: 5011
  • 71 Rehbein J, Leick S, Hiersemann M. J. Org. Chem. 2009; 74: 1531
  • 72 Hiersemann M. Synthesis 2000; 1279
  • 73 Quesada E, Taylor RJ. K. Synthesis 2005; 3193
  • 74 Uyeda C, Jacobsen EN. J. Am. Chem. Soc. 2008; 130: 9228
  • 75 Hurd CD, Sims RJ. J. Am. Chem. Soc. 1949; 71: 2440
  • 76 McLamore WM, Gelblum E, Bavley A. J. Am. Chem. Soc. 1956; 78: 2816
  • 77 For the Claisen rearrangement of 5-allylouracil, see: Otter BA, Taube A, Fox JJ. J. Org. Chem. 1971; 36: 1251
  • 78 Kitahara Y, Funamizu M. Bull. Chem. Soc. Jpn. 1958; 31: 782
  • 79 Holly MM. A, Hobson JD. Tetrahedron Lett. 1970; 11: 3423
  • 80 Dauben WG, Ponaras AA, Chollet A. J. Org. Chem. 1980; 45: 4413
  • 81 Ponaras AA. Tetrahedron Lett. 1980; 21: 4803
  • 82 Ponaras AA. Tetrahedron Lett. 1983; 24: 3
  • 83 Ponaras AA. J. Org. Chem. 1983; 48: 3866
  • 84 Ponaras AA, Meah Y. Tetrahedron Lett. 1986; 27: 4953
  • 85 Wender PA, McDonald FE. J. Am. Chem. Soc. 1990; 112: 4956
  • 86 Wender PA, Mascarenas JL. J. Org. Chem. 1991; 56: 6267
  • 87 Harrington PE, Murai T, Chu C, Tius MA. J. Am. Chem. Soc. 2002; 124: 10091
  • 88 Xiong X, Pirrung MC. Org. Lett. 2008; 10: 1151
    • 89a Overman LE. Angew. Chem., Int. Ed. Engl. 1984; 23: 579
    • 89b Notably the review contains the statement: ‘There are no reported examples of mercury(II) or palladium(II) catalysis of [3,3]-sigmatropic rearrangements of 3-hetero-1,5-dienes. We explored without success the use of mercury(II) trifluoroacetate as a catalyst for the aliphatic Claisen rearrangement and attribute this failure to irreversible binding of the catalyst to the strongly nucleophilic vinylether functional.’
  • 90 Lutz RP. Chem. Rev. 1984; 84: 205
  • 91 Majumdar KC, Alam S, Chattopadhyay B. Tetrahedron 2008; 64: 597
  • 92 Miller WH, Handy NC, Adams JE. J. Chem. Phys. 1980; 72: 99
  • 93 Wiest O, Houk KN. J. Am. Chem. Soc. 1995; 117: 11628
  • 94 The in silico Hurd–Claisen rearrangement of the O-proto-nated parent allyl vinyl ether (3-oxonia Hurd–Claisen rear-rangement) proceeds almost barrierless (B3LYP/6-31+G(d,p) ΔE = 1 4 kcal/mol), see: Hong YJ, Tantillo DJ. Organometallics 2011; 30: 5825
  • 95 For an early report on the rate-accelerating effect of aluminum(III) on the aromatic Claisen rearrangement, see: Petropoulos JC, Tarbell DS. J. Am. Chem. Soc. 1952; 74: 1249
  • 96 For an early letter containing the statement ‘TiC14 did not catalyze the rearrangement of crotyl vinyl ether’ see: Hill RK, Khatri HN. Tetrahedron Lett. 1978; 19: 4337
  • 97 Boeckman RK, Rosario Ferreira MR. d, Mitchell LH, Shao P, Neeb MJ, Fang Y. Tetrahedron 2011; 67: 9787
  • 98 Boeckman RK, del Rosario Rico Ferreira M, Mitchell LH, Shao P. J. Am. Chem. Soc. 2001; 124: 190
  • 99 For an exception to the rule, see: Saito S, Shimada K, Yamamoto H. Synlett 1996; 720
  • 100 Takai K, Mori I, Oshima K, Nozaki H. Tetrahedron Lett. 1981; 22: 3985
  • 101 Takai K, Mori I, Oshima K, Nozaki H. Bull. Chem. Soc. Jpn. 1984; 57: 446
  • 102 Mori I, Takai K, Oshima K, Nozaki H. Tetrahedron 1984; 40: 4013
  • 103 For the application of Me2AlCl, see: Robertson J, Fowler TG. Org. Biomol. Chem. 2006; 4: 4307
  • 104 Boeckman RK, Neeb MJ, Gaul MD. Tetrahedron Lett. 1995; 36: 803
  • 105 Leclercq C, Marko IE. Tetrahedron Lett. 2005; 46: 7229
  • 106 Jia C, Zhang Y, Zhang L. Tetrahedron: Asymmetry 2003; 14: 2195
  • 107 Fukuda Y.-i, Shindo M, Shishido K. Org. Lett. 2003; 5: 749
  • 108 Paquette LA, Sun L.-Q, Friedrich D, Savage PB. J. Am. Chem. Soc. 1997; 119: 8438
  • 109 Paquette LA, Philippo CM. G, Vo NH. Can. J. Chem. 1992; 70: 1356
  • 110 Paquette LA, Friedrich D, Rogers RD. J. Org. Chem. 1991; 56: 3841
  • 111 Wang W, Zhang Y, Zhou H, Bleriot Y, Sinay P. Eur. J. Org. Chem. 2001; 1053
  • 112 Sisu E, Sollogoub M, Mallet J.-M, Sinay P. Tetrahedron 2002; 58: 10189
  • 113 Rychnovsky SD, Lee JL. J. Org. Chem. 1995; 60: 4318
  • 114 Grise CM, Tessier G, Barriault L. Org. Lett. 2007; 9: 1545
  • 115 Ooi T, Takahashi M, Maruoka K. J. Am. Chem. Soc. 1996; 118: 11307
  • 116 Ooi T, Takahashi M, Yamada M, Tayama E, Omoto K, Maruoka K. J. Am. Chem. Soc. 2004; 126: 1150
  • 117 Wipf P, Waller DL, Reeves JT. J. Org. Chem. 2005; 70: 8096
  • 118 Tebbe FN, Parshall GW, Reddy GS. J. Am. Chem. Soc. 1978; 100: 3611
  • 119 Pine SH, Zahler R, Evans DA, Grubbs RH. J. Am. Chem. Soc. 1980; 102: 3270
  • 120 Stevenson JW. S, Bryson TA. Tetrahedron Lett. 1982; 23: 3143
  • 121 Maruoka K, Nonoshita K, Banno H, Yamamoto H. J. Am. Chem. Soc. 1988; 110: 7922
  • 122 For a review on [1,3]-rearrangement of vinyl ethers, see: Nasveschuk CG, Rovis T. Org. Biomol. Chem. 2008; 6: 240
  • 123 Maruoka K, Banno H, Nonoshita K, Yamamoto H. Tetrahedron Lett. 1989; 30: 1265
  • 124 Nonoshita K, Banno H, Maruoka K, Yamamoto H. J. Am. Chem. Soc. 1990; 112: 316
  • 125 Maruoka K, Banno H, Yamamoto H. J. Am. Chem. Soc. 1990; 112: 7791
  • 126 Maruoka K, Banno H, Yamamoto H. Tetrahedron: Asymmetry 1991; 2: 647
  • 127 Maruoka K, Yamamoto H. Synlett 1991; 793
  • 128 Nonoshita K, Maruoka K, Yamamoto H. Bull. Chem. Soc. Jpn. 1992; 65: 541
  • 129 Watanabe WH, Conlon LE. J. Am. Chem. Soc. 1957; 79: 2828

    • For early reports on the palladium(II)-catalyzed enol ether exchange reaction, see:
    • 130a McKeon JE, Fitton P, Griswold AA. Tetrahedron 1972; 28: 227
    • 130b McKeon JE, Fitton P. Tetrahedron 1972; 28: 233
  • 131 Maruoka K, Saito S, Yamamoto H. J. Am. Chem. Soc. 1995; 117: 1165
  • 132 Tayama E, Saito A, Ooi T, Maruoka K. Tetrahedron 2002; 58: 83072
  • 133 Fürstner A, Davies PW. Angew. Chem. Int. Ed. 2007; 46: 3410
  • 134 Grissom JW, Klingberg D, Huang D, Slattery BJ. J. Org. Chem. 1997; 62: 603
  • 135 Mauleon P, Krinsky JL, Toste FD. J. Am. Chem. Soc. 2009; 131: 4513
  • 136 Sherry BD, Maus L, Laforteza BN, Toste FD. J. Am. Chem. Soc. 2006; 128: 8132
  • 137 Sherry BD, Toste FD. J. Am. Chem. Soc. 2004; 126: 15978
  • 138 Menz H, Kirsch SF. Org. Lett. 2006; 8: 4795
  • 139 Harschneck T, Kirsch SF. J. Org. Chem. 2011; 76: 2145
  • 140 Cao H, Jiang H, Mai R, Zhu S, Qi C. Adv. Synth. Catal. 2010; 352: 143
  • 141 Gille A, Rehbein J, Hiersemann M. Org. Lett. 2011; 13: 2122
  • 142 Kende AS, Wustrow DJ. Tetrahedron Lett. 1985; 26: 5411
  • 143 van der Baan JL, Bickelhaupt F. Tetrahedron Lett. 1986; 27: 6267
  • 144 Hayashi T, Yamamoto A, Ito Y. Synth. Commun. 1989; 19: 2109
  • 145 Mikami K, Takahashi K, Nakai T. Tetrahedron Lett. 1987; 28: 5879
  • 146 Mikami K, Takahashi K, Nakai T, Uchimaru T. J. Am. Chem. Soc. 1994; 116: 10948
  • 147 Sugiura M, Nakai T. Tetrahedron Lett. 1996; 37: 7991
  • 148 Yamazaki T, Shinohara N, Kitazume T, Sato S. J. Org. Chem. 1995; 60: 8140
  • 149 Sugiura M, Yanagisawa M, Nakai T. Synlett 1995; 447
  • 150 Sugiura M, Nakai T. Chem. Lett. 1995; 697
  • 151 Hiersemann M. Synlett 1999; 1823
  • 152 Bosch M, Schlaf M. J. Org. Chem. 2003; 68: 5225
  • 153 Wei X, Lorenz JC, Kapadia S, Saha A, Haddad N, Busacca CA, Senanayake CH. J. Org. Chem. 2007; 72: 4250
  • 154 Yatsimirsky AK. Coord. Chem. Rev. 2005; 249: 1997
  • 155 Siebert MR, Tantillo DJ. J. Am. Chem. Soc. 2007; 129: 8686
  • 156 Trost BM, Schroeder GM. J. Am. Chem. Soc. 2000; 122: 3785
  • 157 Trost BM, Dong G, Vance JA. J. Am. Chem. Soc. 2007; 129: 4544
  • 158 Trost BM, Dong G, Vance JA. Chem. Eur. J. 2010; 16: 6265
  • 159 Hiersemann M, Abraham L. Org. Lett. 2001; 3: 49
  • 160 Hiersemann M, Abraham L. Eur. J. Org. Chem. 2002; 1461
  • 161 For a magnesium(II)-promoted Gosteli–Claisen rearrangement, see: Grison C, Olszewski TK, Crauste C, Fruchier A, Didierjean C, Coutrot P. Tetrahedron Lett. 2006; 47: 6583
  • 162 For a bismuth(III)-catalyzed Gosteli–Claisen rearrangement, see: Ollevier T, Mwene-Mbeja TM. Can. J. Chem. 2008; 86: 209
  • 163 Helmboldt H, Hiersemann M. Tetrahedron 2003; 59: 4031
  • 164 Chai Y, Hong S.-p, Lindsay HA, McFarland C, McIntosh MC. Tetrahedron 2002; 58: 2905
  • 165 Ireland RE, Mueller RH. J. Am. Chem. Soc. 1972; 94: 5897
  • 166 Ireland RE, Mueller RH, Willard AK. J. Am. Chem. Soc. 1976; 98: 2868
  • 167 However, for an enantioselective Arnold–Claisen rearrangement of boron enolates, see: Corey EJ, Lee DH. J. Am. Chem. Soc. 1991; 113: 4026
  • 168 Koch G, Kottirsch G, Wietfeld B, Küsters E. Org. Proc. Res. Dev. 2002; 6: 652
  • 169 Takanami T, Hayashi M, Iso K, Nakamoto H, Suda K. Tetrahedron 2006; 62: 9467
  • 170 Takanami T, Hayashi M, Suda K. Tetrahedron Lett. 2005; 46: 2893
  • 171 Curran DP, Kuo LH. Tetrahedron Lett. 1995; 36: 6647
  • 172 Annamalai VR, Linton EC, Kozlowski MC. Org. Lett. 2009; 11: 621
  • 173 Kirsten M, Rehbein J, Hiersemann M, Strassner T. J. Org. Chem. 2007; 72: 4001
  • 174 For a beautiful and groundbreaking non-concerted catalytic asymmetric Hurd–Claisen rearrangement via a π-allyl metal intermediate, see: Geherty ME, Dura RD, Nelson SG. J. Am. Chem. Soc. 2010; 132: 11875
  • 175 Meerwein H, Florian W, Schön N, Stopp G. Liebigs Ann. Chem. 1961; 641: 1
  • 176 Johnson WS, Werthemann L, Bartlett WR, Brocksom TJ, Li T.-T, Faulkner DJ, Petersen MR. J. Am. Chem. Soc. 1970; 92: 741
  • 177 Abraham L, Czerwonka R, Hiersemann M. Angew. Chem. Int. Ed. 2001; 40: 4700
  • 178 Kaden S. Diploma thesis. TU Dresden; Germany: 2002
  • 179 Kaden S, Hiersemann M. Synlett 2002; 1999
  • 180 Abraham L, Körner M, Hiersemann M. Tetrahedron Lett. 2004; 45: 3647
  • 181 Abraham L, Körner M, Schwab P, Hiersemann M. Adv. Synth. Catal. 2004; 346: 1281
  • 182 Pollex A, Hiersemann M. Org. Lett. 2005; 7: 5705
  • 183 Körner M, Hiersemann M. Org. Lett. 2007; 9: 4979
  • 184 Wang Q, Millet A, Hiersemann M. Synlett 2007; 1683
  • 185 Gille A, Hiersemann M. Org. Lett. 2010; 12: 5258
  • 186 Stiasni N, Hiersemann M. Synlett 2009; 2133
  • 187 Balta B, Öztürk C, Aviyente V, Vincent MA, Hillier IH. J. Org. Chem. 2008; 73: 4800
  • 188 Jaschinski T, Hiersemann M. Org. Lett. 2012; 14: 4114
  • 189 Akiyama K, Mikami K. Tetrahedron Lett. 2004; 45: 7217
  • 190 Wender PA, D’Angelo N, Elitzin VI, Ernst M, Jackson-Ugueto EE, Kowalski JA, McKendry S, Rehfeuter M, Sun R, Voigtlaender D. Org. Lett. 2007; 9: 1829
  • 191 Linton EC, Kozlowski MC. J. Am. Chem. Soc. 2008; 130: 16162
  • 192 For an extension to the corresponding propargyl vinyl ethers, see: Cao T, Deitch J, Linton EC, Kozlowski MC. Angew. Chem. Int. Ed. 2012; 51: 2448
  • 193 Cao T, Linton EC, Deitch J, Berritt S, Kozlowski MC. J. Org. Chem. 2012; 77: 11034
  • 194 Uyeda C, Rötheli AR, Jacobsen EN. Angew. Chem. 2010; 122: 9947
  • 195 Marie J.-C, Xiong Y, Min GK, Yeager AR, Taniguchi T, Berova N, Schaus SE, Porco JA. J. Org. Chem. 2010; 75: 4584
  • 196 Kaeobamrung J, Mahatthananchai J, Zheng P, Bode JW. J. Am. Chem. Soc. 2010; 132: 8810
  • 197 Mahatthananchai J, Kaeobamrung J, Bode JW. ACS Catal. 2012; 2: 494
  • 198 Based on DFT calculations and kinetic experiments, it has been concluded that acetylacetonate dicyanomalonate, a cyclic silyl ketene acetal, and a cyclic enamine add in a 1,2-fashion to an a,b-unsaturated acycl azolium; see: Samanta RC, Maji B, De Sarkar S, Bergander K, Fröhlich R, Mück-Lichtenfeld C, Mayr H, Studer A. Angew. Chem. Int. Ed. 2012; 51: 5234
  • 199 Uyeda C, Jacobsen EN. J. Am. Chem. Soc. 2011; 133: 5062
  • 200 Tan J, Cheon C.-H, Yamamoto H. Angew. Chem. 2012; 124: 8389
  • 201 Afarinkia K, Twist AJ, Yu H.-w. J. Org. Chem. 2004; 69: 6500