Journal of the American Chemical Society
Communication
(2) Gabriel, S. Ber. Dtsch. Chem. Ges. 1887, 20, 2224.
(16) (a) Kan, T.; Fukuyama, T. J. Synth. Org. Chem. Jpn. 2001, 59,
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(c) Millburn, R. R.; Snieckus, V. Angew. Chem., Int. Ed. 2004, 43, 892.
(17) Wuts, P. G. M.; Greene, T. W. Protection for the amino group.
In Protective Groups in Organic Synthesis, 4th ed.; John Wiley & Sons:
New York, 2006; pp 696−926.
(3) Reviews: (a) Erdik, E.; Ay, M. Chem. Rev. 1989, 89, 1947.
(b) Narasaka, K.; Kitamura, M. Eur. J. Org. Chem. 2005, 21, 4505.
(c) Ren, Y. J. Theor. Comput. Chem. 2006, 5, 121. Recent examples:
(d) Hatakeyama, T.; Yoshimoto, Y.; Ghorai, S. K.; Nakamura, M. Org.
Lett. 2010, 12, 1516. (e) Matsuda, N.; Hirano, K.; Satoh, T.; Miura, M.
Angew. Chem., Int. Ed. 2012, 51, 3642 and references cited therein.
(4) Selected examples: (a) Nicolaou, K. C.; Duggan, M. E.; Hwang,
C.-K. J. Am. Chem. Soc. 1986, 108, 2468. (b) Brouwn, D. S.; Bruno, M.;
Davenport, R. J.; Ley, S. V. Tetrahedron 1989, 45, 4293. (c) Orita, A.;
Hasegawa, D.; Nakano, T.; Otera, J. Chem.Eur. J. 2002, 8, 2000.
(d) Kitahara, K.; Toma, T.; Shimokawa, J.; Fukuyama, T. Org. Lett.
2008, 10, 2259. (e) Niwa, T.; Yorimitsu, H.; Oshima, K. Tetrahedron
2009, 65, 1971.
(5) High azaphilicity of phosphorus has been revealed by a
substitution reaction of O-(2,4-dinitrophenyl)hydroxylamine; see:
Oae, S.; Yamamoto, F. Tetrahedron Lett. 1973, 14, 5143.
(6) For protection of P(III) by sulfur, see: Clarke, M. L.; Williams, J.
M. J. The synthesis and applications of phosphines. In Organo-
phosphorus Reagents; Murphy, P. J., Ed.; Oxford University Press:
Oxford, 2004; p 26.
(18) Tsunoda, T.; Otsuka, J.; Yamamiya, Y.; Ito, S. Chem. Lett. 1994,
23, 539.
(19) For recent developments in the deprotection of tosylamide, see:
(a) Coeffard, V.; Thobie-Gautier, C.; Beaudet, I.; Le Grognec, E.;
Quintard, J. P. Eur. J. Org. Chem. 2008, 383. (b) Nandi, P.; Redko, M.
Y.; Petersen, K.; Dye, J. L.; Lefenfeld, M.; Vogt, P. F.; Jackson, J. E.
Org. Lett. 2008, 10, 5441. (c) Ankner, T.; Hilmersson, G. Org. Lett.
2009, 11, 503. (d) Shohji, N.; Kawaji, T.; Okamoto, S. Org. Lett. 2011,
13, 2626.
(20) Deprotection of tosylamides with silyllithium was reported by I.
Fleming, et al., although they suggested that the reaction involved a
nucleophilic attack to sulfur; see: Fleming, I.; Frackenpohl, J.; Ila, H. J.
Chem. Soc., Perkin Trans. 1 1998, 1229.
(21) The reaction of 1h and lithium naphthalenide afforded a mixture
of desired p-bromo-N-methylaniline (50%) and N-methylaniline
(35%).
(22) Ishizaki and Hoshino reported that the reaction of tosylamides
and Red-Al in hot toluene afforded the corresponding amines.
Although the reaction mechanism was not described in the literature,
the reaction might proceed via a nucleophilic substitution reaction at
nitrogen; see: Ishizaki, M.; Hoshino, O. J. Org. Chem. 1992, 57, 7285.
(23) The reaction of 1i and Red-Al afforded 4′-hydroxymethyl-N-
methyl-4-toluenesulfonanilide in 74% yield.
(7) It has been reported that the reaction of benzaldehyde
tosylhydrazone and sodium phosphite affords the N-benzylidenehy-
drazide of phosphoric acid diethyl ester; see: Marek, T.; Janusz, R.
Zeitschrift fur Chemie 1990, 30, 246. Marek and Janusz proposed a
̈
Bamford−Stevens-type mechanism for this reaction instead of a
nucleophilic substitution mechanism. Also, we have examined a
reaction of 1a with diethyl phosphite in the presence of sodium
hydride; however, the corresponding substitution product was not
obtained.
(24) 5-exo-Trigonal cyclization of amidyl radicals has been well
studied; for a representative report, see: (a) Horner, J. H.; Musa, O.
M.; Bouvier, A.; Newcomb, M. J. Am. Chem. Soc. 1998, 120, 7738.
Amidyl radical cyclization of allyl carbamate derivatives has been also
reported; see: (b) Nicolaou, K. C.; Baran, P. S.; Zhong, Y.-L.;
Barluenga, S.; Hunt, K. W.; Kranich, R.; Vega, J. A. J. Am. Chem. Soc.
(8) After the reaction of 1a and LiPPh2 followed by extraction of 2a
with ethyl acetate, sulfinic acid was obtained quantitatively from the
water layer after it was acidified with 1 M hydrochloric acid.
(9) It has been reported that the phosphide anion acts as an electron
donor to alkyl halides and causes a radical-mediated substitution
reaction; see: Ashby, E. C.; Gurumurthy, R.; Ridlehuber, R. W. J. Org.
Chem. 1993, 58, 5832 and references cited therein. Accordingly, we
considered the possibility of a similar radical mechanism for the
present reaction and performed mechanistic studies (vide infra).
(10) Rossi and colleagues have reported a photostimulated reaction
of R2NTs and the phosphide anion in liquid ammonia, which provides
the substitution product in good to moderate yields. They concluded
that the reaction proceeded through a radical mechanism; see:
2002, 124, 2233. (c) Schulte-Wulwer, I. A.; Helaja, J.; Gottlich, R.
̈
̈
Synthesis 2003, 1886.
(25) To confirm the possibility of the radical cyclization of A, we
examined the copper(I) promoted reaction of the corresponding
chloroamide according to Gottlich’s procedure (ref 24c). As a result, 5-
̈
exo-trigonal cyclization product 16 (Y = Cl) was obtained in 57% yield
along with 15 (11%). This result supports our proposed mechanism;
see Supporting Information for details.
(26) This calculation was performed at the B3LYP/6-311G(d,p) level
of theory with Gaussian 03.
(27) The zero-point energy difference between the reactant complex
and the transition state.
́
(a) Foray, G. S.; Penenory, A. B.; Rossi, R. A. J. Phys. Org. Chem. 1995,
̃ ̃
́
8, 356. (b) Foray, G. S.; Penenory, A. B.; Rossi, R. A. Can. J. Chem.
̃ ̃
1999, 77, 676. In contrast, our reaction does not require
photostimulation. Indeed, the substitution reaction of Et2NTs and
KPPh2 proceeds smoothly in THF under light-shielded conditions.
(11) (a) Clarke, M. L.; Williams, J. M. J. The synthesis and
applications of phosphines. In Organophosphorus Reagents; Murphy, P.
J., Ed.; Oxford University Press: Oxford, 2004; pp 15−48. For a recent
development in preparation of phosphide anion, see: (b) Nandi, P.;
Dye, J. L.; Bentley, P.; Jackson, J. E. Org. Lett. 2009, 11, 1689.
(12) It is reasonable to consider that KPPh2 was generated in situ,
based on the pKa value of HPPh2. The reported pKa value of HPPh2 is
23.8 in THF; see: Abdur-Rashid, K.; Fong, T. P.; Greaves, B.; Gusev,
D. G.; Hinman, J. G.; Landau, S. E.; Lough, A. J.; Morris, R. H. J. Am.
Chem. Soc. 2000, 122, 9155.
(13) (a) Chen, W.; Mbafor, W.; Roberts, S. M.; Whittall, J. J. Am.
Chem. Soc. 2006, 128, 3922 and references cited therein. (b) Ona-
̃
Burgos, P.; Fernan
́ ́
dez, I.; Roces, L.; Torre-Fernandez, L.; García-
Granda, S.; Lopez-Ortiz, F. Org. Lett. 2008, 10, 3195.
́
(14) For cleavage of N−P bonds, see: (a) Toth, I.; Hanson, B. E.;
Davis, M. E. Organometallics 1990, 9, 675. (b) Koizumi, T.; Amitani,
H.; Yoshii, E. Synthesis 1979, 110 and ref 11.
(15) Although 0.1 M hydrochloric acid was strong enough to cleave
the N−P bond in place of 1 M hydrochloric acid, the cleavage did not
proceed with saturated aqueous NH4Cl.
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