170302-87-1Relevant articles and documents
Synthesis of nitrogen bridgehead bicyclic heterocycles via ring-closure of β-ammonio 5-hexenyl radicals
Della, Ernest W.,Knill, Andrew M.
, p. 7529 - 7533 (2007/10/03)
The 2-(3-methylenepiperidinyl)ethyl radical (6) displays considerable reluctance to ring-closure under conditions which its carbocyclic analog, the 2-(3-methylenecyclohexyl)ethyl radical (2), cyclizes essentially completely. Molecular mechanics calculations suggest that the increased activation barrier associated with ring-closure of 6 is the result of a higher than expected transition state energy. A study of the behavior of β-ammonio-substituted 5-hexenyl radicals, such as the 3,3-dimethyl-3-azonia-5-hexenyl radical (22), reveals that cyclization occurs readily. Treatment of 1-methyl-1-(2-(phenylselenyl)ethyl)-3-methylenepiperidinium iodide (20) with tributyltin hydride in tert-amyl alcohol yields the bridgehead nitrogen bicyclic heterocycle, 1,5-dimethyl-1-azoniabicyclo-[3.2.1]octane iodide (26), in excellent yield and without contamination, thus providing an attractive synthetic route to this hitherto unknown heterocyclic system.
ENZYME-MEDIATED ENANTIOSELECTIVE ACYLATION OF SECONDARY AMINES IN ORGANIC SOLVENTS
Asensio, Gregorio,Andreu, Cecilia,Marco, J. Alberto
, p. 4197 - 4198 (2007/10/02)
Porcine pancreatic lipase (PPL) and lipase Amano P catalyze the enantioselective acylation of cyclic 1,2- and 1,3-amino alcohol derivatives in organic solvents.The enantiomeric excesses (ee's) were shown to depend on the enzyme, reaction time, temperature and type of substrate.