Phyllis A. Leber
Franklin & Marshall College
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Featured researches published by Phyllis A. Leber.
Organic and Biomolecular Chemistry | 2008
Jack E. Baldwin; Phyllis A. Leber
Molecular rearrangements through thermal [1,3] carbon shifts, such as vinylcyclopropane-to-cyclopentene and vinylcyclobutane-to-cyclohexene isomerizations, were recognized and exemplified repeatedly from 1960-1964. Serious mechanistic studies of these and related rearrangements over the past 40 years have provided ample grounds for interpreting them as processes taking place by way of conformationally flexible but not statistically equilibrated diradical intermediates. Orbital symmetry theory fails to account for the stereochemical characteristics of [1,3] carbon shifts. For sigmatropic reactions of this class the theory can no longer be retained as a valid basis for mechanistic interpretations, or even as a serious contender for consideration as a mechanistic possibility.
Synthetic Communications | 1986
Jeffrey D. Burkey; Phyllis A. Leber; Lisa S. Silverman
Abstract A cyclobutanone to cyclobutane conversion has been performed on 7-methyl-7-vinylbicyclo[3.2.0]hept-2-en-6-one by low-temperature (25°C) Wolff-Kishner reduction of the hydrazone derivative. Upon heating, the exo-vinyl epimer affords predominantly cis-6-methyl-4,7,8,9-tetrahydroindene.
Plant Physiology and Biochemistry | 2000
Richard A. Fluck; Phyllis A. Leber; John D. Lieser; Sandra K. Szczerbicki; Jeffrey G. Varnes; Melissa A. Vitale; Erin E. Wolfe
We synthesized the choline conjugates of three derivatives of phenylacetic acid, four derivatives of phenoxyacetic acid, and of naphthalene-1-acetic acid and measured the effects of these conjugates on pea (Pisum sativum L. cv. Alaska) stem segment elongation. We also synthesized the thioester analogs of six choline conjugates and measured their rates of hydrolysis by pea cholinesterase and their rates of spontaneous hydrolysis. With one exception, conjugates that stimulated growth were hydrolyzed at high rates by pea cholinesterase, while conjugates that were hydrolyzed at low rates by pea cholinesterase did not stimulate growth. The results are consistent with a model in which cholinesterase releases active auxins from these conjugates.
Tetrahedron Letters | 1994
Timothy E. Glass; Phyllis A. Leber; Patricia L. Sandall
Abstract The title compound, when subjected to gas-phase pyrolysis at 275°C, undergoes predominantly fragmentation to cyclopentadiene and isobutylene.
Tetrahedron Letters | 2001
Jack E. Baldwin; Phyllis A. Leber
Abstract endo -6-Methylbicyclo[3.2.0]hept-2-ene at 275°C in the gas phase isomerizes and fragments with a first-order rate constant for disappearance of 7.3×10 −6 s −1 . The exo -methyl isomer is not formed; the ring inversion isomerization of the bicyclo[3.2.0]hept-2-ene is not kinetically competitive.
Tetrahedron Letters | 1986
Mark A. Forman; Phyllis A. Leber
Abstract Gas-phase thermolysis of the title compound in the temperature range of 150°–166°C yields predominantly cis -6-methyl-4,7,8,9-tetrahydroindene by tandem [1,3]–[3,3) sigmatropic shifts: however, we cannot exclude some direct conversion by an alternative [1,3] sigmatropic migration.
Phytochemistry | 1995
Balázs A. Bozsó; Richard A. Fluck; Rachel A. Jameton; Phyllis A. Leber; Jeffrey G. Varnes
Abstract A two-step synthetic strategy affords indole-3-acetylcholine (IAC) from indole-3-acetic acid (IAA) via the intermediacy of 2-dimethylaminoethyl indole-3-acetate. Thus, treatment of indole-3-acetate with 1-dimethylamino-2-chloroethane, followed by methylation with methyl iodide, yields 55–70% recrystallized IAC from IAA. Using the same methodology, six analogues of IAC have been prepared in overall yields ranging from 40 to 60%.
Tetrahedron Letters | 1990
Timothy E. Glass; Phyllis A. Leber
Abstract Gas-phase pyrolysis of the endo -vinyl epimer (1 A ) of the title compound at 275°C affords predominantly 3-(2-methyl-2-butenyl)cyclopentene (presumably the Z isomer), a direct [1,5]-hydrogen shift product, whereas the exo -vinyl epimer (1 B ) favors the fragmentation products, cyclopentene and isoprene.
Journal of Organic Chemistry | 2012
Phyllis A. Leber; George R. Mann; William Hancock-Cerutti; Matthew F. Wipperman; Sylvia Zohrabian; Ryan M. Bell; Jack E. Baldwin
cis,anti,cis-Tricyclo[7.4.0.0(2,8)]tridec-10-ene (13TCT) undergoes [1,3] sigmatropic rearrangements at 315 °C in the gas phase to the si product 1 and to the sr product 2 with si/sr = 2.1. The dominant thermal isomerization process, however, is epimerization at C8 to afford product 3. That stereomutation at C8 occurs 50% faster than the si and sr shifts combined.
Synthetic Communications | 1989
Timothy E. Glass; Susan J. Klein; Phyllis A. Leber
Abstract Alkylation of 7-endo-ethylbicyclo[3.2.0]hept-2-en-6-one (2a) and 7-endo-methylbicyclo[3.2.0]hept-2-en-6-one (2b) with lithium diisopropylamide (LDA) and the appropriate alkyl iodide (methyl and ethyl iodide, respectively) afforded the title compound such that alkylation had occurred exclusively on the exo face of the bicyclo[3.2.0] system.