Stereoselective Synthesis of Bioactive Compounds
(Track)
Use of “halo vinyl aldehydes” in organic synthesis and chemo selective functional group transformations in gamma lactam derivatives
Jayanta Kumar Ray
Department of Chemistry, Indian Institute of Technology, Kharagpur-721302, West Bengal, India
Abstract:
Chloro and bromo vinyl aldehydes have been used as starting material for the synthesis of different small ring heterocyclic systems with exo-cyclic functionalities.1-2 Highly regioselective direct alkylation/arylation methods have also been developed to functionalize the heterocyclic compounds. 3 Core and fine tuning of structural motifs generated interesting host molecules to embrace neutral guest in the cavity by weak electrostatic interactions.4
Carbocyclic frame works have also been achieved from bromo vinyl aldehydes by sequential use of Ullmann Cross coupling and McMurry coupling reactions.5 Pd catalysed Ullmann cross coupling reactions have been utilized to synthesise bio-active natural products. Annulated bromovinyl aldehydes were converted to 5-7 member cyclic ketones by Heck-type reaction.6,7 Base catalysed cyclo condensation of active methylene compounds with bromo vinyl aldehydes generated novel substituted benzo derivatives. Shortest synthesis of Cuparene from bromoaldehydes has also been achieved.
The uses of the methodology developed have been explored for the synthesis of bioactive natural and designed molecules.8-10
The gamma-lactam derivatives have been synthesized by intermolecular Michael addition followed by intramolecular amidification reaction in one pot. The method is useful to generate functionality in all the five atoms of the gamma-lactam unit. The stereo controlled chemo selective functional group transformations and antibacterial activities of the synthesized compounds will be presented. Highly regio - selective carbenoid insertion reaction to sp2 C-H bond have also been developed to achieve new heterocyclic frame works. Redox reactions of Pyrroles and gamma lactams have been studied11-15 to design chemo selective transformations. CAN mediated decarboxylative hydroxylation have recently been developed. Mechanistic details will be presented.
References:
1. S. Brahma and J. K Ray Tetrahedron Report No 829, 64 (13)2883- 2896, 2008.
2. S. Brahma and J.K. Ray Tetrahedron Letters 46, 6575 (2005)
3. B.P.Dutta, G.K. Kar and J.K. Ray Tetrahedron Letters 44 ,8641(2003)
4. S. Brahma, D. Pan and J. K. Ray Supramolecular Chemistry 16, 447 ( 2004 )
5. Rathin Jana, Subhankar Samanta and Jayanta K. Ray Tetrahedron Letters 49, 851(2008).
6. S. K. Mal, D. Ray and J.K. Ray Tetrahedron Letters 45 , 277 (2004)
7. D. Ray, S. K. Mal and J. K. Ray Synlet 2135 (2005)
8. Jana, Rathin; Chatterjee, Indranil; Samanta, Shubhankar; Ray,Jayanta K
Organic Letters 10, 4795 (2008) .
9. Shubhankar Samanta, Hemakesh Mohapatra, Rathin Jana and Jayanta K. Ray
Tetrahedron Letters 49, 7153(2008)
10. Devalina Ray and Jayanta K. Ray Organic Letters 9 (2) 191 (2007)
11. Devalina Ray, Sunanda Pal, Sulagna Brahma and Jayanta K Ray
Tetrahedron Letters 48, 8005 ( 2007)
12.. P.Haldar, J. Guin and J. K Ray Tetrahedron Leters 46, 1071 (2005)
13. Gopa Barman , Mahuya Roy and Jayanta K Ray Tetrahedron Letters 49, 1405 (2008)
14. P. Haldar and J. K. Ray Organic Letters 7 , 4341 ( 2005 )
15. Pranab Haldar and Jayanta K. Ray Tetrahedron Letters 49, 3659 (2008)
