react with the carbonate anion to give a water-soluble adduct
and be washed out in an aqueous workup.
conversion in 72 h), and using either K2CO3 or Li2CO3 as
the base gave no reaction. When 9a was treated with Cs2CO3
in MeCN/D2O and heated at reflux for 18 h the recovered
starting material had the -NCH2CO2Me portion converted
into -NCD2CO2Me, thus providing evidence for a E1cB
mechanism for the reaction, the slow step being the breaking
of the N-N bond.13
The N,N′-diethoxycarbonyl hydrazines 9-18 (see the
Supporting Information for their synthesis and references)
were N-alkylated using methyl bromoacetate12 in dry MeCN
and Cs2CO3 at 50 °C to give 9a-13a and 16a-18a,
respectively, in the indicated yields, Scheme 3. In general,
it proved beneficial to isolate and purify these compounds
prior to the elimination step. In the case of compounds 14
and 15, the same alkylation was carried out at reflux (ca. 82
°C) and led directly to the elimination products 14b (97%)
and 15b (98%), respectively.
In all of the reactions to form the carbamates we have not
detected the imine 8 or its hydrate.
The conversions of 11a f 11b, 12a f 12b, 13a f 13b,
and 17a f 17b are noteworthy since the use of reductive
reaction conditions to cleave the N-N bond would be
expected to result in competitive reduction of the enone,
styrene, and benzylic amine, respectively.
This method of cleaving the N-N′-bond has the potential
to find wide use in the conversion of hydrazines (and
derivatives) into amines (and derivatives) under mild non-
reducing reaction conditions.
The adduct 9a and Cs2CO3 in dry MeCN was heated at
reflux for 18 h to give the carbamate 9b (91%). If water is
present in the reaction the elimination is very slow (ca. 15%
(7) Polymethylhydrosiloxane, Pd-C, (Boc)2O: Chandrasekhar, S.; Red-
dy, C. R.; Rao, R. J. Synlett 2001, 156, 1–1562.
(8) For an oxidative method of cleaving the N-N bond, see: Ferna´ndez,
R.; Ferrete, A.; Lassaletta, J. M.; Llera, J. M.; Monge, A. Angew. Chem.,
Int. Ed 2000, 39, 2893–2897. Ferna´ndez, R.; Ferrete, A.; Lassaletta, J. M.;
Llera, J. M.; Mart´ın-Zamora, E. Angew. Chem., Int. Ed. 2002, 41, 831–
833. (b) Ferna´ndez, R.; Ferrete, A.; Llera, J. M.; Magriz, A.; Mart´ın-Zamora,
E.; D´ıaz, E.; Lassaletta, J. M. Chem.sEur. J. 2004, 10, 737–745.
(9) References to eliminative cleavage of N-N bonds in acyclic systems
: Adam, W.; Pastor, A.; Wirth, T. Org. Lett. 2000, 2, 1295–1297. Gong,
Y.; Bausch, M. J.; Wang, L. Tetrahedron Lett. 2001, 42, 1–4. Toure´, B. B.;
Hall, D. G. J. Org. Chem. 2004, 69, 8429–8436. References to eliminative
cleavage of N-N bonds in cyclic systems: Taylor, E. C.; Davies, H. M. L.
J. Org. Chem. 1986, 51, 1537–1540. Forrest, A. K.; Schmidt, R. R.
Tetrahedron Lett. 1984, 25, 1769–1772.
Acknowledgment. The Welch Chair (F-0018) is thanked
for their support of this research, and the MDS Research
Foundation, Inc., is thanked for a postdoctoral Fellowship
(K.A.S.).
Supporting Information Available: Complete experi-
mental details and compound characterization. This material
(10) Unpublished results.
(11) Jung, M. E.; Shishido, K.; Light, L.; Davis, L. Tetrahedron Lett.
1981, 22, 4607–4610. Abood, N. A.; Nosal, R. Tetrahedron Lett. 1994, 35,
3669–3672.
OL902313V
(12) The use of other alkylating agents such as phenacyl bromide gave
complex mixtures.
(13) Kice, J. L; Kupczyk-Subotkowska, L. J. Org. Chem. 1990, 55,
1523–1527.
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