Abstract
The cyclodehydration of Bohlmann-Rahtz aminodienones is catalysed by iodine in ethanol at room temperature to give 2,3,6-trisubstituted pyridines in excellent yield, with total regiocontrol and without the need for chromatographic purification.
Key words
pyridines - enamines - heterocycles - Bohlmann-Rahtz
References
1
Bohlmann F.
Rahtz D.
Chem. Ber.
1957,
90:
2265
2
Bagley MC.
Dale JW.
Bower J.
Synlett
2001,
1149
3
Bagley MC.
Lunn R.
Xiong X.
Tetrahedron Lett.
2002,
43:
8331
4
Bagley MC.
Dale JW.
Hughes DD.
Ohnesorge M.
Phillips NG.
Bower J.
Synlett
2001,
1523
5
Bagley MC.
Chapaneri K.
Xiong X.
Tetrahedron Lett.
2004,
45:
6121
6
Bagley MC.
Dale JW.
Bower J.
Chem. Commun.
2002,
1682
7
Bagley MC.
Hughes DD.
Sabo HM.
Taylor PH.
Xiong X.
Synlett
2003,
1443
8
Bagley MC.
Brace C.
Dale JW.
Ohnesorge M.
Phillips NG.
Xiong X.
Bower J.
J. Chem. Soc., Perkin Trans. 1
2002,
1663
9
Bagley MC.
Hughes DD.
Lloyd R.
Powers VEC.
Tetrahedron Lett.
2001,
42:
6585
10
Hughes DD.
Bagley MC.
Synlett
2002,
1332
11a
Bagley MC.
Dale JW.
Ohnesorge M.
Xiong X.
Bower J.
J. Comb. Chem.
2003,
5:
41
11b
Bashford KE.
Burton MB.
Cameron S.
Cooper AL.
Hogg RD.
Kane PD.
MacManus DA.
Matrunola CA.
Moody CJ.
Robertson AAB.
Warne MR.
Tetrahedron Lett.
2003,
44:
1627
12a
Bagley MC.
Xiong X.
Org. Lett.
2004,
6:
3401
12b
Adamo MFA.
Adlington RM.
Baldwin JE.
Pritchard GJ.
Rathmell RE.
Tetrahedron
2003,
59:
2197
12c
Adlington RM.
Baldwin JE.
Catterick D.
Pritchard GJ.
Tang LT.
J. Chem. Soc., Perkin Trans. 1
2000,
2311
12d
Baldwin JE.
Catterick D.
Pritchard GJ.
Tang LT.
J. Chem. Soc., Perkin Trans. 1
2000,
303
12e
Moody CJ.
Bagley MC.
Synlett
1998,
361
13a
Moody CJ.
Bagley MC.
Synlett
1998,
361
13b
Bagley MC.
Bashford KE.
Hesketh CL.
Moody CJ.
J. Am. Chem. Soc.
2000,
122:
3301
13c
Moody CJ.
Bagley MC.
Chem. Commun.
1998,
2049
14
Bagley MC.
Dale JW.
Jenkins RL.
Bower J.
Chem. Commun.
2004,
102
15a
Bagley MC.
Dale JW.
Xiong X.
Bower J.
Org. Lett.
2003,
5:
4421
15b Bagley, M. C.; Chapaneri, K.; Dale, J. W.; Xiong, X.; Bower, J. J. Org. Chem. 2005 , 70 , in review.
16
Bagley MC.
Glover C.
Merritt EA.
Xiong X.
Synlett
2004,
811
17
General Procedure for the Catalytic Cyclodehydration of Aminodienones 3 Using I
2
.
A solution of aminodienone 3 (0.2 mmol, 1 equiv) and iodine (0.04 mmol, 20 mol%) in EtOH (4 mL) was stirred at r.t. for 30 min and an aq solution of Na2 S2 O3 (10% w/v, 10 mL) was added. The mixture was extracted with CH2 Cl2 (3 × 20 mL) and the organic extracts were combined, dried (Na2 SO4 ) and evaporated in vacuo to give pyridine 4 .
18 Pyridines 4a -h exhibited physical and spectroscopic properties that were in agreement with literature data (see refs. 1, 8, 11a, and 15b for detailed information).