20 Summary and Outlook
In summary, we have gathered information from the recent published methodologies,
wherein heterogeneous or reusable copper-catalyst systems were used for the
C (aryl) –N bond formation employing aryl halides and arylboronic acids as coupling
partners. Among the methods we discussed here for the arylation of aryl halides,
most of the reactions were conducted at 100–160
C. To our knowledge no roomtemperature reports have appeared under heterogeneous conditions.
The challenges and opportunities in copper-catalyzed heterogeneous catalysis
are enormous as less research was carried out compared to homogeneous systems
[4, 90]. The development of less expensive and robust new catalysts with higher
activities and turnover numbers is desirable. It is also important to exploit these
heterogeneous catalysts for the synthesis of biologically important molecules.
References
1. Yin LX, Liebscher J (2007) Chem Rev 107:133
2. Thomas AW, Ley SV (2009) In: Ackerman L (ed) Modern arylation methods, 4th edn. WileyVCH, Weinheim, p 121 (Chapter 4)
3. Sheldon RA (2008) Chem Commun 3352
4. Evano G, Blanchard N, Toumi M (2008) Chem Rev 108:3054
5. Ma D, Zhang Y, Yao J, Wu S, Tao F (1998) J Am Chem Soc 120:12459
6. Clement JB, Hayes JF, Sheldrake HM, Sheldrake PW, Wells AS (2001) Synlett 1423
7. Ma D, Xia C, Jiang J, Zhang J, Tang W (2003) J Org Chem 68:442
8. Brackman F, Es-Sayed M, de Meijere A (2005) Eur J Org Chem 2250
9. Mallesham B, Rajesh BM, Reddy PR, Srinivas D, Trehan S (2003) Org Lett 5:963
10. Scheiper B, Glorius F, Leitner A, Furstner A (2004) Proc Natl Acad Sci USA 101:11960
11. Ghosh A, Sieser JE, Caron S, Couturier M, Dupont-Gaudet K, Girardin M (2006) J Org Chem
71:1258
12. Chae J, Buchwald SL (2004) J Org Chem 69:3336
13. Huang WS, Shakespeare WC (2007) Synthesis 2121
14. Pu YM, Ku YY, Grieme T, Black LA, Bhatia AV, Cowart M (2007) Org Proc Res Dev
11:1004
15. Lv X, Wang Z, Bao W (2006) Tetrahedron 62:4756
16. Wang Z, Bao W, Jiang Y (2005) Chem Commun 2849
17. Rout L, Jammi S, Punniamurthy T (2007) Org Lett 9:3397
18. Huang YZ, Miao H, Zhang QH, Chen C, Xu J (2008) Catal Lett 122:344
19. Choudary BM, Sridhar CH, Lakshmi Kantam M, Venkanna GT, Sreedhar B (2005) J Am
Chem Soc 127:9948
NH 2
X
R
1
R
2
NCS
Cu(I) catalyst (2.5% mol)
DABCO, toluene
60 °C, 8 h
+
R
1
S
N
NHR
2
Scheme 25 Synthesis of 2-aminobenzothiazoles from 2-halobenzeneamines and phenyl
isothiocyanates catalyzed by Cu(I) catalyst
Recent Developments in Recyclable Copper Catalyst Systems for C–N Bond. . .
169
In summary, we have gathered information from the recent published methodologies,
wherein heterogeneous or reusable copper-catalyst systems were used for the
C (aryl) –N bond formation employing aryl halides and arylboronic acids as coupling
partners. Among the methods we discussed here for the arylation of aryl halides,
most of the reactions were conducted at 100–160
C. To our knowledge no roomtemperature reports have appeared under heterogeneous conditions.
The challenges and opportunities in copper-catalyzed heterogeneous catalysis
are enormous as less research was carried out compared to homogeneous systems
[4, 90]. The development of less expensive and robust new catalysts with higher
activities and turnover numbers is desirable. It is also important to exploit these
heterogeneous catalysts for the synthesis of biologically important molecules.
References
1. Yin LX, Liebscher J (2007) Chem Rev 107:133
2. Thomas AW, Ley SV (2009) In: Ackerman L (ed) Modern arylation methods, 4th edn. WileyVCH, Weinheim, p 121 (Chapter 4)
3. Sheldon RA (2008) Chem Commun 3352
4. Evano G, Blanchard N, Toumi M (2008) Chem Rev 108:3054
5. Ma D, Zhang Y, Yao J, Wu S, Tao F (1998) J Am Chem Soc 120:12459
6. Clement JB, Hayes JF, Sheldrake HM, Sheldrake PW, Wells AS (2001) Synlett 1423
7. Ma D, Xia C, Jiang J, Zhang J, Tang W (2003) J Org Chem 68:442
8. Brackman F, Es-Sayed M, de Meijere A (2005) Eur J Org Chem 2250
9. Mallesham B, Rajesh BM, Reddy PR, Srinivas D, Trehan S (2003) Org Lett 5:963
10. Scheiper B, Glorius F, Leitner A, Furstner A (2004) Proc Natl Acad Sci USA 101:11960
11. Ghosh A, Sieser JE, Caron S, Couturier M, Dupont-Gaudet K, Girardin M (2006) J Org Chem
71:1258
12. Chae J, Buchwald SL (2004) J Org Chem 69:3336
13. Huang WS, Shakespeare WC (2007) Synthesis 2121
14. Pu YM, Ku YY, Grieme T, Black LA, Bhatia AV, Cowart M (2007) Org Proc Res Dev
11:1004
15. Lv X, Wang Z, Bao W (2006) Tetrahedron 62:4756
16. Wang Z, Bao W, Jiang Y (2005) Chem Commun 2849
17. Rout L, Jammi S, Punniamurthy T (2007) Org Lett 9:3397
18. Huang YZ, Miao H, Zhang QH, Chen C, Xu J (2008) Catal Lett 122:344
19. Choudary BM, Sridhar CH, Lakshmi Kantam M, Venkanna GT, Sreedhar B (2005) J Am
Chem Soc 127:9948
NH 2
X
R
1
R
2
NCS
Cu(I) catalyst (2.5% mol)
DABCO, toluene
60 °C, 8 h
+
R
1
S
N
NHR
2
Scheme 25 Synthesis of 2-aminobenzothiazoles from 2-halobenzeneamines and phenyl
isothiocyanates catalyzed by Cu(I) catalyst
Recent Developments in Recyclable Copper Catalyst Systems for C–N Bond. . .
169