References
1
Kabalka GW.
Guchhait SK.
Org. Lett.
2003,
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4129
2a
Zawadzki S.
Zwierzak A.
Polish J. Chem.
2003,
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315
2b
Tubrik O.
Mäeorg U.
Ragnarsson U.
Tetrahedron Lett.
2002,
6213
2c
Tubrik O.
Mäeorg U.
Org. Lett.
2001,
3:
2297
3a
Smith PAS.
The Chemistry of Open Chain Nitrogen Compounds
Vol. 2:
W. A. Benjamin;
New York:
1966.
Chap. 9.
3b
Sidgwick NV.
Organic Chemistry of Nitrogen
3rd ed.:
Oxford University Press;
London:
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Chap. 15.
3c
Timberlake JW.
Stowell JC. In Chemistry of Hydrazo-, Azo-, and Azoxy Groups
Patai S.
Wiley;
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Chap. 4.
4
Ghali NI.
Venton DL.
Hung SC.
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Zawadski S.
Osowska-Pacewicka K.
Zwierzak A.
Synth. Commun.
1987,
485
6 The alkylation conditions described in ref.5 have also been used for N-alkylation of N-substitued carboxamides. See: Koziara A.
Zawadzki S.
Zwierzak A.
Synth. Commun.
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7 Hydrazine 3c was prepared on 1 mol scale (68% overall yield) without any modification of the experimental procedure. In addition, a differential scanning calorimetry (DSC) test established compound 1 to be chemically stable in the temperature range described in the reaction conditions.
8 Alkylations with allyl and benzyl chlorides were performed under identical conditions as those described for alkyl bromides with comparable yields and purities.
9 The stock solutions of hydrazines have been stored in amber vials at room temperature for up to 1 year with no noticeable loss of molarity.
10
Experimental Procedure for the Preparation of
t
-Butyl Isopropylidene Carbazate (1): Added MgSO4 (ca. 2 g) and 5 drops of HOAc to a solution of tert-butyl carbazate (10 g, 75.6 mmol) in acetone (75 mL). The mixture was heated to reflux for 1 h then cooled, filtered and concd in vacuo to give 12.58 g (97%) of a white solid. Mp 85-87 °C.; lit. mp2a 85-87 °C. 1H NMR (300 MHz, CDCl3): δ = 7.46 (br s, 1 H), 1.97 (s, 3 H), 1.77 (s, 3 H), 1.45 (s, 9 H). 13C NMR (300 MHz, CDCl3): δ = 16.1, 25.5, 28.4, 81.0, 150.0, 153.1.
11
2a (R =
n
-propyl): 1H NMR (300 MHz, CDCl3): δ = 3.45 (t, J = 7.4 Hz, 2 H), 2.06 (s, 3 H), 1.86 (s, 3 H), 1.48 (m, 2 H), 1.44 (s, 9 H), 0.88 (t, J = 7.4 Hz, 3 H). 2b (R = 2-fluoro-ethyl): 1H NMR (300 MHz, CDCl3): δ = 4.56 (t, J = 5.1 Hz, 1 H), 4.40 (t, J = 5.1 Hz, 1 H), 3.86 (t, J = 5.1 Hz, 1 H), 3.78 (t, J = 5.1 Hz, 1 H), 2.07 (s, 3 H), 1.90 (s, 3 H), 1.46 (s, 9 H). 2c (R = cyclopropylmethyl): 1H NMR (300 MHz, CDCl3): δ = 3.36 (d, J = 6.9 Hz, 2 H), 2.08 (s, 3 H), 1.91 (s, 3 H), 1.45 (s, 9 H), 0.96 (m, 1 H), 0.43 (m, 2 H), 0.20 (m, 2 H). 2d (R = 2-ethoxyethyl): 1H NMR (300 MHz, CDCl3): δ = 3.69 (t, J = 6.3 Hz, 2 H), 3.48 (m, 4 H), 2.06 (s, 3 H), 1.88 (s, 3 H), 1.45 (s, 9 H), 1.16 (t, J = 7.1 Hz, 3 H). 2e (R = 3-propynyl): 1H NMR (300 MHz, CDCl3): δ = 4.24 (d, J = 2.3 Hz, 2 H), 2.18 (t, J = 2.3 Hz, 1 H), 2.10 (s, 3 H), 1.92 (s, 3 H), 1.46 (s, 9 H). 2f (R = benzyl): 1H NMR (300 MHz, CDCl3): δ = 7.29 (m, 5 H), 4.68 (s, 2 H), 2.03 (s, 3 H), 1.70 (s, 3 H), 1.45 (s, 9 H).
12
3a (R =
n
-propyl): 1H NMR (300 MHz, d
6-DMSO): δ = 2.84 (t, J = 7.7 Hz, 2 H), 1.57 (m, 2 H), 0.88 (t, J = 7.5 Hz, 3 H). 13C NMR (300 MHz, d
6-DMSO): δ = 11.1, 18.1, 52.2. 3b (R = 2-fluoroethyl): 1H NMR (300 MHz, d
6-DMSO): δ = 4.60 (dt, J = 47.2, 4.7 Hz, 2 H), 3.19 (dt, J = 28.0, 4.7 Hz, 2 H). 13C NMR (300 MHz, d
6-DMSO): δ = 49.6 (d, J = 20 Hz), 80.5 (d, J = 166 Hz). 3c (R = cyclopropylmethyl): 1H NMR (300 MHz, d
6-DMSO): δ = 2.78 (d, J = 7.5 Hz, 2 H), 1.01 (m, 1 H), 0.52 (m, 2 H), 0.31 (m, 2 H). 13C NMR (300 MHz, d
6-DMSO): δ = 3.7, 6.4, 55.3. 3d (R = 2-ethoxyethyl): 1H NMR (300 MHz, d
6-DMSO): δ = 3.56 (t, J = 5.5 Hz, 2 H), 3.45 (q, J = 7.0 Hz, 2 H), 3.05 (t, J = 5.5 Hz, 2 H), 1.12 (t, J = 7.0 Hz, 3 H). 13C NMR (300 MHz, d
6-DMSO): δ = 15.0, 49.6, 65.7. 3e (R = 3-propynyl): 1H NMR (300 MHz, d
6-DMSO): δ = 3.68 (d, J = 2.4 Hz, 2 H), 3.40 (t, J = 2.4 Hz, 1 H). 13C NMR (300 MHz, d
6-DMSO): δ = 39.1, 77.6, 78.8. 3f (R = benzyl): 1H NMR (300 MHz, d
6-DMSO): δ = 7.45-7.30 (m, 5 H), 4.06 (s, 2 H). 13C NMR (300 MHz, d
6-DMSO): δ = 54.3, 128.8, 129.1, 130.1, 134.6.
