About

The research efforts in the laboratory are divided into two general areas.

Alkaloids:

The long standing interest, developed over some 50 years of study (see, e.g. Dalton, D. R., “An Approach to the Total Synthesis of Lycorine”, Ph. D. Dissertation, Univ. Calif., L..A., 1962 ; Hendrickson, J.B.; Alder, R.W.: Dalton, D.R.; and Hey, D.G.. “Some Approaches to Total Synthesis of Lycorine”, J. Org. Chem. 1969, 34, 2667;  Dalton, D. R. “The Alkaloids, A Biogenetic Approach” M. Dekker, Inc., New York (1979), of the rich chemistry of alkaloids (Dalton, D.R.; Mascavage, L. M.; Wilson, M. L. Eirk-Othmer Encyclopedia of Chemical Technology, 5th edit., Vol 2., 2004,  71) coupled to what we continue to learn about the processes by which these compounds form and how they might be used in medicine powers current efforts in the modification of morphinane structures. So, we are looking at the less widely studied A-ring as indicated in our recent reports (Wilson, M. L.; Dalton, D. R.; Carroll, P.J. “Decoration of the Aromatic Ring of Dihydrocodeinone (Hydrocodone) and 14-Hydroxydihydrocodeinone (Oxycodone)”. J. Org. Chem. 2005, 70, 6492. and Mascavage, L.M.; Wilson, M. L.; Dalton, D. R. “Syntheses of Morphine and Codeine (1992 – 2002): Templates for Exploration of Synthetic Tools.” Current Organic Synthesis 2006 , 3, 99).

Surface Catalyzed Gas Phase Kinetics:

The second effort derives from the lust to learn the details of product forming molecular interactions. Many efforts to define such pathways or mechanisms of simple reactions between gases have demonstrated both that (a) simple pathways are rare and (b) products can form, simultaneously, by different pathways (Rettner, C. T.; Auerbach, D. J. Science, 1994, 263, 365.). Indeed, the latter appears common  when surfaces (which are everywhere) can participate via adsorbed species to form the same products as formed between non-adsorbed species. Our work continues along two pathways

First, we are continuing to examine the reaction between gaseous hydrogen chloride and gaseous alkenes and alkynes (L. M. Mascavage, L. M.; Zhang F.; Dalton, D. R. “The Reaction of the Gases Hydrogen Chloride and 2-Butyne.” J. Org. Chem. 1994, 59, 5048) with our current (and continuing efforts) directed toward vinylacetylene (buta-1-yne-3-ene). Secondly, we are now examining, surface catalyzed reactions between aldehydes and amines (Mascavage, L.M.; Sonnet. P.E.;  Dalton, D.R.”On the Surface-Catalyzed Reaction between the Gases 2,2-Dimethylpropanal and Methanamine. Formation of Active-Site Imines.” J. Org. Chem. 2006, (DOI 10.1021/jo052503z ) 71) both experimentally and computationally.

Recent work extends these ideas through many examples found in the protein data bank (http://www.rcsb.org/pdb/home/home.do) and the publication itself is available at Bioorg. Med. Chem. Let. 2008,18, 744.

Gaseous mixtures of HCl and vinylacetylene were permitted to react in Pyrex IR cells (NaCl windows).  Gaseous 4-chloro-1,2-butadiene and 2-chloro-1,3-butadiene (chloroprene) were the major products. Kinetic data (FT-IR) generated a rate expression in concert with surface catalysis. Computational studies involving surface associated water provide a view that accounts for the experimentally determined orders and a bifurcated pathway producing both produce. The results are in accord with wall-absorbed reactant(s) and previously reported computational studies.

L.M. Mascavage, R. Zhang-Plasket, P.E. Sonnet and D. R. Dalton, “Gas phase surface-catalyzed HCl to vinylacetylene: motion along a catalytic surface. Experiment and theory.” Tetrahedron, 2008, 64, 9357.

 

 

 

Post a Comment

You must be logged in to post a comment.