Polyethylene glycol mediated facile protocol for N-Cbz protection of amines

References

• Clark , J. and Macquarrie , D.M.A. 2002 . Handbook of Green Chemistry , 1 – 531 . Blackwell : Oxford .
   Google Scholar
• Tanaka , K. Solvent-Free Organic Synthesis ; Wiley-VCH Weinheim 2003 ; pp 1 – 402 .
   Google Scholar
• Li , C.J. 2005 . Organic Reactions in Aqueous Media with a Focus on Carbon–Carbon Bond Formations: A Decade Update . Chem. Rev , 105 : 3095 – 3165 .
   PubMed Web of Science ®Google Scholar
• Koichi , M. Green Reaction Media for Organic Synthesis ; Wiley–VCH Weiheim 2005 ; pp 9 – 58 .
   Google Scholar
• Jain , L.S. , Singhal , S. and Sain , B. 2007 . PEG Assisted Solvent and Catalyst free Synthesis of 3,4-dihydropyrimidinones under Mild Reaction Conditions . Green Chem , 9 : 740 – 741 .
   Web of Science ®Google Scholar
• Fieser , L.F. and Fieser , M. 1967 . In Reagents for Organic Synthesis, Vol. 1 , 109 New York : John Wiley & Sons .
   Google Scholar
• Berkowitz , D.B. and Pedersen , M.L. 1994 . Simultaneous Amino and Carboxyl Group Protection for.alpha.-Branched Amino Acids . J. Org. Chem , 59 : 5476 – 5478 .
   Web of Science ®Google Scholar
• Maligres , P.E. , Houpis , I. , Rossen , K. , Molina , A. , Sager , J. , Upadhyay , V. , Wells , K.M. , Reamer , R.A. , Lynch , J.E. , Askin , D. , Volante , R.P. and Reider , P.J. 1997 . Synthesis of the Orally active Spiroindoline-based Growth Hormone Secretagogue, MK-677 . Tetrahedron , 32 : 10983 – 10992 .
   Web of Science ®Google Scholar
• Hernandez , J.N. and Martin , V.S. 2004 . First Practical Protection of (-Amino Acids as N,N-Benzyloxycarbamoyl Derivatives . J. Org. Chem , 69 : 3590 – 3592 .
   PubMed Web of Science ®Google Scholar
• Greene , T.W. and Wuts , P.G.M. 1998 . Protective Groups in Organic Synthesis , 531 – 539 . Wiley : New York .
   Google Scholar
• Kumar , P.V. , Reddy , M.S. , Narender , M. , Surendra , K. , Nageswar , Y.V. D. and Rao , K.R. 2006 . Aqueous Phase Mono-Protection of Amines and Amino Acids as N-benzyloxycarbonyl Derivatives in the Presence of β-Cyclodextrin . Tetrahedron Lett , 47 : 6393 – 6396 .
   Web of Science ®Google Scholar
• Varala , R. , Enugala , R. and Adapa , S.R. 2007 . Molecular Iodine-Catalyzed Efficient N-Cbz Protection of Amines . J. Iran. Chem. Soc , 4 : 370 – 374 .
   Web of Science ®Google Scholar
• Suresh Babu , K. , Subba Rao , V.R. , Ranga Rao , R. , Sivaram Babu , S. and Madhusudana Rao , J. 2009 . A Mild and Efficient Chemoselective N-Benzyloxycarbonylation of Amines using TBAB as a Catalyst under Solvent-Free Conditions . Can. J. Chem , 87 : 393 – 396 .
   Web of Science ®Google Scholar
• Dendrinos , K.G. and Kalivretenos , A.G. 1998 . Convenient Protection of Amines as Carbamates using Polymer-bound HOBT as Catalyst . J. Chem. Soc. Perkin Trans , 1 : 1463 – 1464 .
   Google Scholar
• Chem , J. , Spear , S.K. , Huddleston , J.G. and Rogers , R.D. 2005 . Polyethylene Glycol and Solutions of Polyethylene Glycol as Green Reaction Media . Green Chem. , 7 : 64 – 82 .
   Web of Science ®Google Scholar
• Sheftel , V.O. Indirect Food Additives and Polymers: Migration and Toxicology . Lewis 2000 , 1114 – 1116 .
   Google Scholar
• Claudia , F.-P. 2005 . Safety Assessment on Polyethylene Glycol (PEGs) and their Derivatives as used in Cosmetic Products . Toxicology , 214 : 1 – 38 .
   PubMed Web of Science ®Google Scholar
• Vasudevan , V.N. and Varma , R.S. 2001 . Microwave-accelerated Suzuki cross-Coupling Reaction in Polyethylene Glycol (PEG) . Green Chem , 3 : 146 – 148 .
   Web of Science ®Google Scholar
• Chandrasekhar , S. , Narsihmulu , C. , Sultana , S.S. and Reddy , N.R. 2002 . Poly(ethylene glycol) (PEG) as a Reusable Solvent Medium for Organic Synthesis. Application in the Heck Reaction . Organic Lett , 4 : 4399 – 4401 .
   PubMed Web of Science ®Google Scholar
• Haimov , A. ; Newmann , R. Polyethylene Glycol as a non-ionic Liquid Solvent for Polyoxometalate Catalyzed Aerobic Oxidation . Chem. Commun . 2002 , 876 – 877 .
   PubMed Web of Science ®Google Scholar
• Mukhopadhyay , C. and Tapaswi , P.K. 2008 . PEG-mediated Catalyst-Free Expeditious Synthesis of 2-substituted Benzimidazoles and Bis-Benzimidazoles under Solvent-less Conditions . Tetrahedron Lett , 49 : 6237 – 6240 .
   Web of Science ®Google Scholar
• He , F. , Li , S. , Vert , M. and Zhuo , R. 2003 . Enzyme-Catalyzed Polymerization and Degradation of Copolymers Prepared from ϵ- Caprolactone and Poly(ethylene glycol) . Polymer , 44 : 5145 – 5151 .
   Web of Science ®Google Scholar
• Wei , W. , Wang , Y.H. , Jiang , J.Y. and Jin , Z.L. 2007 . A Novel Phosphate Ligand Used for the Rh-catalyzed Hydroformylation of Cyclohexene in a Thermoregulated PEG Biphase System . Chinees Chem. Lett , 8 : 933 – 935 .
   Web of Science ®Google Scholar
• Kidwai , M. , Bhatnagar , D. and Neeraj , K.M. 2010 . Polyethylene Glycol (PEG) Mediated Green Synthesis of 2,5-Disubstituted 1,3,4-Oxadiazoles Catalyzed by Ceric Ammonium Nitrate (CAN) . Green Chem. Lett. Rev , 3 : 55 – 59 .
   Web of Science ®Google Scholar
• Kidwai , M. , Mishra , N.K. , Bhatnagar , D. and Jahan , A. 2011 . A Green Methodology for One-Pot Synthesis of Polysubstituted-Tetrahydropyrimidines using PEG . Green Chem. Lett. Rev , 4 : 109 – 115 .
   Web of Science ®Google Scholar
• Kidwai , M.. and Bhatnagar , D. 2010 . Ceric Ammonium Nitrate (CAN) Catalyzed Synthesis of N-substituted Decahydroacridine- 1,8-diones in PEG . Tetrahedron Lett , 51 : 2700 – 2703 .
   Web of Science ®Google Scholar
• Kidwai , M. , Jahan , A. and Bhatnagar , D. 2010 . Polyethylene Glycol as an Efficient and Reusable Solvent Medium for the Synthesis of Thiohydantoins using K2CO3 as Catalyst . J. Sulf. Chem , 31 : 161 – 167 .
   Web of Science ®Google Scholar
• Kidwai , M. , Jahan , A. and Bhatnagar , D. 2010 . Polyethylene Glycol: A Recyclable Solvent System for the Synthesis of Benzimidazole Derivatives using CAN as Catalyst . J. Chem. Sci , 122 : 607 – 612 .
   Web of Science ®Google Scholar
• Maheswara , M. , Siddaiah , V. , Damu , G.L.V. and Venkata Rao , C. 2006 . An Efficient One-pot Synthesis of Polyhydroquinoline Derivatives via Hantzsch Condensation using a Heterogeneous Catalyst under Solvent-Free Conditions . ARKIVOC , ii : 201 – 206 .
   Google Scholar
• Maheswara , M. ; Siddaiah , V. ; Gopalaiah , K. ; Madhava Rao , V. ; Venkata Rao , C. A Simple and Effective Glycine-Catalyzed Procedure for the Preparation of Oximes . J. Chem. Res . June 2006 , 362 – 363 .
   Web of Science ®Google Scholar
• Maheswara , M. , Siddaiah , V. , Koteswara Rao , Y. , Yew-Min Tzeng , Y.-T. and Sridhar , C. 2006 . A Simple and Efficient One-Pot Synthesis of 1,4-Dihydropyridines Using Heterogeneous Catalyst under Solvent-Free Conditions . J. Mol. Cat. A: Chemical , 260 : 179 – 180 .
   Web of Science ®Google Scholar
• Siddaiah , V. , Basha , G.M. , Padma Rao , G. , Viplava Prasad , U. and Suryachendra Rao , R. 2010 . PEG-mediated Facile Protocol for N-Boc Protection of Amines . Chem. Lett , 39 : 1127 – 1129 .
   Web of Science ®Google Scholar