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1.  Radical [3+2]-Annulation of Divinylcyclopropanes: Rapid Synthesis of Complex Meloscine Analogs 
Organic letters  2013;16(1):94-97.
A radical [3+2]-divinylcyclopropane annulation cascade has been extended to encompass five D-ring variants of the meloscine/epimeloscine core structure. Representative ABCD tetracyclic intermediates were further elaborated with novel substituted E-rings through subsequent transformations of advanced intermediates that provided opportunities for late-stage variation of the B- ring (lactam) N-substituents which were also developed.
PMCID: PMC3910537  PMID: 24313360
2.  Radical cyclizations of cyclic ene sulfonamides occur with β-elimination of sulfonyl radicals to form polycyclic imines 
Journal of the American Chemical Society  2013;135(44):10.1021/ja408387d.
Radical cyclizations of cyclic ene sulfonamides provide stable bicyclic and tricyclic aldimines and ketimines in good yields. Depending on the structure of the precursor, the cyclizations occur to provide fused and spirocyclic imines with five-, six-, and seven-membered rings. The initial radical cyclization produces an α-sulfonamidoyl radical that undergoes elimination to form the imine and a phenylsulfonyl radical. In a related method, 3,4-dihydroquinolines can also be produced by radical translocation reactions of N-(2-iodophenylsulfonyl)tetrahydroisoquinolines. In either case, very stable sulfonamides are cleaved to form imines (rather than amines) under mild reductive conditions.
PMCID: PMC3868638  PMID: 24111991
3.  Rotational isomers of N-methyl-N-arylacetamides and their derived enolates: implications for asymmetric Hartwig oxindole cyclizations 
The Journal of organic chemistry  2013;78(8):4083-4089.
The rotational preferences of N-(2-bromo-4,6-dimethylphenyl)-N-methyl 2-phenyl-propanamide were studied as a model of precursors for Hartwig asymmetric oxindole cyclizations. The atropisomers of this compound were separated by flash chromatography, then the enantiomers were resolved and the interconversions of the stereocenter and the N–Ar axis were studied. Under thermal conditions, the axis is very stable. Under the basic conditions of the Hartwig cyclization, both the stere-ocenter and the chiral axis equilibrate via enolate formation. The N–Ar rotation barrier of a 2-phenylacetamide analog was reduced from 31 kcal mol−1 in the precursor to 17 kcal mol−1 in the enolate. Reasons for this dramatic barrier reduction and implications of both N–Ar and amide C–N rotations for Hartwig cyclizations are discussed.
PMCID: PMC3653423  PMID: 23534372
4.  Tri-tert-butyl 3-oxo-4-oxa-1,8,11-tri­aza­spiro­[5.6]dodecane-1,8,11-tri­acetate 
The title compound, C26H45N3O8, is a bicyclic mol­ecule; the seven-membered diazepane ring has a twisted-chair conformation and the six-membered morpholine ring has a boat conformation.
PMCID: PMC2850304  PMID: 20354302
5.  Synthesis of highly enantioenriched 3,4-dihydroquinolin-2-ones by 6-exo-trig radical cyclizations of axially chiral α-halo-ortho-alkenyl anilides 
Journal of the American Chemical Society  2009;131(42):15492-15500.
Radical cyclizations (Bu3SnH, Et3B/air, rt) of racemic α-halo-ortho-alkenyl anilides provide 3,4-dihydroquinolin-2-ones in high yield. Cyclizations of enantioenriched precursors occur in similarly high yields and with transfer of axial chirality to the new stereocenter of the products with exceptionally high fidelity (often > 95%). Single and tandem cyclizations of α-halo-ortho-alkenyl anilides bearing an additional substituent on the α-carbon occur with high chirality transfer and high diastereoselectivity. Straightforward models are proposed to interpret both the chirality transfer and diastereoselectivity aspects. These first examples of an approach for axial chiral transfer from a reactive species in the amide to an acceptor suggest broad potential for extension both within and beyond radical reactions.
PMCID: PMC2784126  PMID: 19799432
6.  Synthesis and biological evaluation of the first pentafluorosulfanyl analogs of mefloquine† 
Organic & biomolecular chemistry  2009;7(20):4163-4165.
Two novel SF5 analogs of the antimalarial agent mefloquine were synthesized in 5 steps and 10–23% overall yields and found to have improved activity and selectivity against malaria parasites. This work also represents the first report of SF5-substituted quinolines.
PMCID: PMC2929370  PMID: 19795052
7.  Fluorous Parallel Synthesis of a Piperazinedione-Fused Tricyclic Compound Library 
A fluorous-linker-assisted solution-phase protocol has been developed and applied to parallel synthesis of a piperazinedione-fused tricyclic compound library. The one-pot [3 + 2] cycloaddition of fluorous amino esters, aldehydes, and maleimides afforded bicyclic proline derivatives. The intermediates were subjected to N-acylation with chloroacetyl chloride, followed by displacement reactions with amines. Linker cleavage with concomitant lactamization yielded the final products. Microwave heating was employed to facilitate several reaction steps and fluorous solid phase extraction (F-SPE) was employed to purify the intermediates. During the method development, a small library containing sixteen analogs was prepared. The optimized conditions were applied to the synthesis of a production library containing ninety analogs.
PMCID: PMC2921976  PMID: 19301852

Results 1-7 (7)