Organic transformations mechanically induced

Mechanically Induced Organic Transformations in a Ball-mill... 

Chander Mohan was born in 1975 at Dhariwal, Punjab, India. He received his B.Pharm. and M.Tech.(Pharm.) in bulk drugs from Guru Nanak Dev University and the National Institute of Pharmaceutical Education and Research (NIPER), Mohali. After that he worked as senior chemist at Dr. Reddy s Research Foundation, Hyderabad. He then joined Professor M. P. Mahajan s research group in 2002 for his doctoral studies. His research is focused on the synthesis and chemical transformation of C-5/C-6-substituted pyrimidinones. His research interests include synthesis of medicinally important molecules, transition metal-induced transformations in organic synthesis, reaction mechanism and total synthesis of natural products. 

Surface-catalyzed degradation of pesticides has been examined in the context of research on contaminant-clay interactions. Such interactions were observed initially when clay minerals were used as carriers and diluents in the crop protection industry (Fowker et al. 1960). Later specific studies on the persistence of potential organic contaminants in the subsurface defined the mechanism of clay-induced transformation of organophosphate insecticides (Saltzman et al. 1974 Mingelgrin and Saltzman 1977) and s-triazine herbicides (Brown and White 1969). In both cases, contaminant degradation was attributed to the surface acidity of clay minerals, controlled by the hydration status of the system. 

Lehman-McKeeman, L.D. Gamsky, E.A. (2000) Choline supplementation inhibits diethanolamine-induced morphological transformation in Syrian hamster embiyo cells evidence for a carcinogenic mechanism. Toxicol. Sci., 55, 303-310 Levin, J.O., Andersson, K. Hallgren, C. (1994) Exposure to low molecular polyamines during road paving. Ann. occup. Hyg., 38, 257-264 Lide, D.R. Milne, GW. A. (1996) Properties of Organic Compounds, Version 5.0 [CD-ROM], Boca Raton, FL, CRC Press... 

Copper-catalyzed [2 + 2] photocycloadditions are related to the latter reactions. These transformations have been extensively studied, frequently in the context of application to organic synthesis [21], When irradiated in the presence of copper(I) triflate, norbomene 12 was effidently transformed into its dimer 13 (Scheme 5.3, reaction 4) [22]. Although complexes such as III are involved in the reaction mechanism [22, 23], it is unclear whether MLCT (metal to ligand charge transfer) or LMCT (ligand to metal charge transfer) excitation induces the transformation. 

Photochemically induced [2 + 2] cycloaddition is of extraordinary importance in organic synthesis,as this is a method ideally suited for the preparation of sterically congested compounds. The reaction may occur by a concerted mechanism allowed by rules of orbital symmetry, or, more often, via a biradical pathway. For preparative purposes, the most widely exploited is the enone-alkene photochemical [2 + 2] cycloaddition. This reaction proceeds with high regioselectivity, although its stereoselectivity might be low. The first example of the utilization of this reaction for the synthesis of a natural compound, a-cariophyllene 385, was described by Corey (Scheme 2.129). Adduct 386, formed as a mixture of stereoisomers in high yield from simple precursors, was further transformed via the tricyclic intermediate 387 into the... 

---