@article {3742,
	title = {On the conformational analysis and photochemical reactivity of 1,6-cyclodecanedione},
	journal = {Molecular Crystals and Liquid Crystals Science and Technology Section a-Molecular Crystals and Liquid Crystals},
	volume = {276},
	year = {1996},
	note = {ISI Document Delivery No.: UJ432Times Cited: 0Cited Reference Count: 2712th International Conference on the Chemistry of the Organic Solid State (ICCOSS XII)JUL 09-14, 1995MATSUYAMA, JAPANMinist Educ, Japan, Ehime Univ, Chem Soc Japan, Soc Synthet Organ Chem, Japan},
	pages = {A289-A298},
	type = {Proceedings Paper},
	abstract = {Photolysis of 1,5-cyclodecanedione, both in the crystalline state and in solution, fails to lead to any Norrish/Yang type II products despite the fact that the conformation of the molecule in the solid state is nearly ideal for hydrogen atom abstraction. Based on X-ray crystal structure and molecular modeling studies, it is argued that gamma-hydrogen abstraction does occur in the solid state, but that closure of the resulting 1,4-biradical is slower than reverse hydrogen atom transfer owing to difficulty in forming the expected 8-membered ring-containing photoproduct. In solution, on the other hand, molecular mechanics calculations indicate that the lack of photoreactivity of 1,5-cyclodecanedione stems from the fact that this molecule exists nearly exclusively in a conformation for which gamma-hydrogen abstraction is sterically impossible.},
	keywords = {ABSTRACTION, C-H...O, II REACTIONS, KETONES, MOLECULAR MECHANICS METHODOLOGY},
	isbn = {1058-725X},
	url = {<Go to ISI>://A1996UJ43200083},
	author = {Lewis, T. J. and Rettig, S. J. and Sauers, R. R. and Scheffer, J. R. and Trotter, J. and Wu, C. H.}
}
@article {3742,
	title = {On the conformational analysis and photochemical reactivity of 1,6-cyclodecanedione},
	journal = {Molecular Crystals and Liquid Crystals Science and Technology Section a-Molecular Crystals and Liquid Crystals},
	volume = {276},
	year = {1996},
	note = {ISI Document Delivery No.: UJ432Times Cited: 0Cited Reference Count: 2712th International Conference on the Chemistry of the Organic Solid State (ICCOSS XII)JUL 09-14, 1995MATSUYAMA, JAPANMinist Educ, Japan, Ehime Univ, Chem Soc Japan, Soc Synthet Organ Chem, Japan},
	pages = {A289-A298},
	type = {Proceedings Paper},
	abstract = {Photolysis of 1,5-cyclodecanedione, both in the crystalline state and in solution, fails to lead to any Norrish/Yang type II products despite the fact that the conformation of the molecule in the solid state is nearly ideal for hydrogen atom abstraction. Based on X-ray crystal structure and molecular modeling studies, it is argued that gamma-hydrogen abstraction does occur in the solid state, but that closure of the resulting 1,4-biradical is slower than reverse hydrogen atom transfer owing to difficulty in forming the expected 8-membered ring-containing photoproduct. In solution, on the other hand, molecular mechanics calculations indicate that the lack of photoreactivity of 1,5-cyclodecanedione stems from the fact that this molecule exists nearly exclusively in a conformation for which gamma-hydrogen abstraction is sterically impossible.},
	keywords = {ABSTRACTION, C-H...O, II REACTIONS, KETONES, MOLECULAR MECHANICS METHODOLOGY},
	isbn = {1058-725X},
	url = {<Go to ISI>://A1996UJ43200083},
	author = {Lewis, T. J. and Rettig, S. J. and Sauers, R. R. and Scheffer, J. R. and Trotter, J. and Wu, C. H.}
}
@article {3687,
	title = {Geometric requirements for hydrogen abstractability and 1,4-biradical reactivity in the Norrish/Yang type II reaction: Studies based on the solid state photochemistry and X-ray crystallography of medium-sized ring and macrocyclic diketones},
	journal = {Journal of the American Chemical Society},
	volume = {118},
	number = {26},
	year = {1996},
	note = {ISI Document Delivery No.: UV292Times Cited: 41Cited Reference Count: 76},
	month = {Jul},
	pages = {6167-6184},
	type = {Article},
	abstract = {The Norrish/yang type II photochemistry of ten even-numbered cyclic diketones ranging in ring size from 10-membered to 26-membered has been studied in the crystalline state as well as in solution, In the solid state, the diketones undergo stereoselective cyclobutanol formation in which the cis or trans ring fusion stereochemistry of the photoproducts is governed by the conformation of the diketone present in the crystal as determined by X-ray crystallography. The reactive gamma-hydrogen atoms are identified and the distance and angular parameters associated with their abstraction are derived from the crystallographic data. For the most part, the abstractions occur through boatlike rather than chairlike six-atom geometries, and the average value of d, the C=O ... H abstraction distance, for 16 reactive gamma-hydrogens was found to be 2.74 +/- 0.04 Angstrom; the average values of the angular parameters omega (the gamma-hydrogen out-of-plane angle), Delta (the C=O ... H-gamma angle), and theta (the C-H gamma ... O angle) are 53 +/- 5 degrees, 83 +/- 4 degrees, and 115 +/- 2 degrees, respectively. In a similar manner, the geometric parameters associated with the ring closure reactions of the intermediate 1,4-hydroxy biradicals were estimated from the crystallographic data. This indicates that both the pre-cis and pre-trans biradicals are poorly aligned for cleavage but are well oriented for closure, with radical separations of 3.1-3.2 Angstrom. For four of the diketones, the solid state photoproduct ratios were found to be temperature dependent as a result of enantiotropic phase transitions. For two of the diketones, the high-temperature, metastable phases were characterized by solid state C-13 and H-2 NMR spectroscopy. Crystals of 1,14-cyclohexacosanedione were found to be dimorphic, and the conformation adopted by the macrocycle is very different in the two dimorphs. As a result, irradiation of one of the dimorphs leads to cis-cyclobutanol and photolysis of the other gives trans, a particularly clear demonstration of the effect of conformational polymorphism on solid state chemical reactivity. Overall, the solid state results indicate that the product distribution is determined by the relative rates of forward rather than reverse hydrogen atom transfer and that the biradicals react in a least-motion, conformation-specific manner. In solution, on the other hand, the photoreaction is ring size-dependent, resembling the solid state results for the 12- and 14-membered-ring diketones, and consisting mainly of type II elimination accompanied by reduced amounts of nonstereoselective cyclobutanol formation for the 16-26-membered-ring compounds. It is suggested that this ring size dependence stems from the relative conformational freedom of the intermediate 1,4-biradicals in the fluid medium-motions that are slow compared to closure for the 12- and 14-membered rings, but that permit alignment for biradical cleavage and alternative modes of closure in the {\textquoteright}{\textquoteright}floppier{\textquoteright}{\textquoteright} 16-membered and larger rings. The one exception to the above generalizations is 1,6-cyclodecanedione, which was found to be photochemically inert both in the solid state and solution despite having a crystal conformation favorable for type II photochemistry. Possible reasons for this behavior are presented and discussed.},
	keywords = {ATOM TRANSFERS, C-H...O, CONFORMATION, CYCLOALKANONES, CYCLODODECANONE, CYCLOHEXADECANE, MOLECULAR MECHANICS METHODOLOGY, PHENYL KETONES, PHOTOPROCESSES, TRANSITION STRUCTURES},
	isbn = {0002-7863},
	url = {<Go to ISI>://A1996UV29200012},
	author = {Gudmundsdottir, A. D. and Lewis, T. J. and Randall, L. H. and Scheffer, J. R. and Rettig, S. J. and Trotter, J. and Wu, C. H.}
}
@article {3687,
	title = {Geometric requirements for hydrogen abstractability and 1,4-biradical reactivity in the Norrish/Yang type II reaction: Studies based on the solid state photochemistry and X-ray crystallography of medium-sized ring and macrocyclic diketones},
	journal = {Journal of the American Chemical Society},
	volume = {118},
	number = {26},
	year = {1996},
	note = {ISI Document Delivery No.: UV292Times Cited: 41Cited Reference Count: 76},
	month = {Jul},
	pages = {6167-6184},
	type = {Article},
	abstract = {The Norrish/yang type II photochemistry of ten even-numbered cyclic diketones ranging in ring size from 10-membered to 26-membered has been studied in the crystalline state as well as in solution, In the solid state, the diketones undergo stereoselective cyclobutanol formation in which the cis or trans ring fusion stereochemistry of the photoproducts is governed by the conformation of the diketone present in the crystal as determined by X-ray crystallography. The reactive gamma-hydrogen atoms are identified and the distance and angular parameters associated with their abstraction are derived from the crystallographic data. For the most part, the abstractions occur through boatlike rather than chairlike six-atom geometries, and the average value of d, the C=O ... H abstraction distance, for 16 reactive gamma-hydrogens was found to be 2.74 +/- 0.04 Angstrom; the average values of the angular parameters omega (the gamma-hydrogen out-of-plane angle), Delta (the C=O ... H-gamma angle), and theta (the C-H gamma ... O angle) are 53 +/- 5 degrees, 83 +/- 4 degrees, and 115 +/- 2 degrees, respectively. In a similar manner, the geometric parameters associated with the ring closure reactions of the intermediate 1,4-hydroxy biradicals were estimated from the crystallographic data. This indicates that both the pre-cis and pre-trans biradicals are poorly aligned for cleavage but are well oriented for closure, with radical separations of 3.1-3.2 Angstrom. For four of the diketones, the solid state photoproduct ratios were found to be temperature dependent as a result of enantiotropic phase transitions. For two of the diketones, the high-temperature, metastable phases were characterized by solid state C-13 and H-2 NMR spectroscopy. Crystals of 1,14-cyclohexacosanedione were found to be dimorphic, and the conformation adopted by the macrocycle is very different in the two dimorphs. As a result, irradiation of one of the dimorphs leads to cis-cyclobutanol and photolysis of the other gives trans, a particularly clear demonstration of the effect of conformational polymorphism on solid state chemical reactivity. Overall, the solid state results indicate that the product distribution is determined by the relative rates of forward rather than reverse hydrogen atom transfer and that the biradicals react in a least-motion, conformation-specific manner. In solution, on the other hand, the photoreaction is ring size-dependent, resembling the solid state results for the 12- and 14-membered-ring diketones, and consisting mainly of type II elimination accompanied by reduced amounts of nonstereoselective cyclobutanol formation for the 16-26-membered-ring compounds. It is suggested that this ring size dependence stems from the relative conformational freedom of the intermediate 1,4-biradicals in the fluid medium-motions that are slow compared to closure for the 12- and 14-membered rings, but that permit alignment for biradical cleavage and alternative modes of closure in the {\textquoteright}{\textquoteright}floppier{\textquoteright}{\textquoteright} 16-membered and larger rings. The one exception to the above generalizations is 1,6-cyclodecanedione, which was found to be photochemically inert both in the solid state and solution despite having a crystal conformation favorable for type II photochemistry. Possible reasons for this behavior are presented and discussed.},
	keywords = {ATOM TRANSFERS, C-H...O, CONFORMATION, CYCLOALKANONES, CYCLODODECANONE, CYCLOHEXADECANE, MOLECULAR MECHANICS METHODOLOGY, PHENYL KETONES, PHOTOPROCESSES, TRANSITION STRUCTURES},
	isbn = {0002-7863},
	url = {<Go to ISI>://A1996UV29200012},
	author = {Gudmundsdottir, A. D. and Lewis, T. J. and Randall, L. H. and Scheffer, J. R. and Rettig, S. J. and Trotter, J. and Wu, C. H.}
}
@article {3035,
	title = {CRYSTAL STRUCTURE-REACTIVITY CORRELATIONS IN THE SOLID-STATE PHOTOCHEMISTRY OF N-(TERT-BUTYL)SUCCINIMIDE},
	journal = {Canadian Journal of Chemistry-Revue Canadienne De Chimie},
	volume = {72},
	number = {9},
	year = {1994},
	note = {ISI Document Delivery No.: PJ994Times Cited: 5Cited Reference Count: 20},
	month = {Sep},
	pages = {1952-1960},
	type = {Article},
	abstract = {In order to provide experimental evidence on the stereoelectronic requirements for intramolecular hydrogen atom abstraction by carbonyl oxygen, N-(tert-butyl)succinimide, 1, was investigated by the crystal structure - reactivity correlation method. In this method, the success or failure of a given reaction in the crystalline state is correlated with the geometric parameters associated with the process as determined by X-ray crystallography. In the case of N-(tert-butyl)succinimide, the crystal and molecular structure shows that the molecule adopts a conformation in which there are very close contacts (d = 2.17-2.24 Angstrom) between the carbonyl oxygen atoms and certain gamma-hydrogen atoms on the tert-butyl group. In accord with these close contacts, ultraviolet irradiation of N-(tert-butyl)succinimide in the crystalline state leads to transfer of one of the gamma-hydrogen atoms from carbon to oxygen. This produces a 1,4-biradical which closes to form a cyclobutanol, and the cyclobutanol undergoes ring opening to afford the final stable product, tetrahydro-1H-azepine-2,5-dione, 2. The crystal and molecular structure of photoproduct 2 is also reported. In contrast to many solid state transformations, there was no discernable melting of the crystals during reaction, and complete conversions of 1 into 2 could be achieved. The isolated chemical yield of photoproduct 2 from the solid state reaction (79\%) is in fact considerably higher than that reported by Kanaoka and Hatanaka for the corresponding solution phase process (49\%). This permitted the solid state reaction to be followed to 100\% conversion by X-ray powder diffractometry, which showed that the process is a single crystal-to-polycrystalline transformation involving a regular and progressive conversion of 1 into 2 with no obvious diffraction peaks that might be attributable to the intermediate cyclobutanol.},
	keywords = {C-H...O, SYSTEMS},
	isbn = {0008-4042},
	url = {<Go to ISI>://A1994PJ99400010},
	author = {Fu, T. Y. and Scheffer, J. R. and Trotter, J.}
}
@article {3035,
	title = {CRYSTAL STRUCTURE-REACTIVITY CORRELATIONS IN THE SOLID-STATE PHOTOCHEMISTRY OF N-(TERT-BUTYL)SUCCINIMIDE},
	journal = {Canadian Journal of Chemistry-Revue Canadienne De Chimie},
	volume = {72},
	number = {9},
	year = {1994},
	note = {ISI Document Delivery No.: PJ994Times Cited: 5Cited Reference Count: 20},
	month = {Sep},
	pages = {1952-1960},
	type = {Article},
	abstract = {In order to provide experimental evidence on the stereoelectronic requirements for intramolecular hydrogen atom abstraction by carbonyl oxygen, N-(tert-butyl)succinimide, 1, was investigated by the crystal structure - reactivity correlation method. In this method, the success or failure of a given reaction in the crystalline state is correlated with the geometric parameters associated with the process as determined by X-ray crystallography. In the case of N-(tert-butyl)succinimide, the crystal and molecular structure shows that the molecule adopts a conformation in which there are very close contacts (d = 2.17-2.24 Angstrom) between the carbonyl oxygen atoms and certain gamma-hydrogen atoms on the tert-butyl group. In accord with these close contacts, ultraviolet irradiation of N-(tert-butyl)succinimide in the crystalline state leads to transfer of one of the gamma-hydrogen atoms from carbon to oxygen. This produces a 1,4-biradical which closes to form a cyclobutanol, and the cyclobutanol undergoes ring opening to afford the final stable product, tetrahydro-1H-azepine-2,5-dione, 2. The crystal and molecular structure of photoproduct 2 is also reported. In contrast to many solid state transformations, there was no discernable melting of the crystals during reaction, and complete conversions of 1 into 2 could be achieved. The isolated chemical yield of photoproduct 2 from the solid state reaction (79\%) is in fact considerably higher than that reported by Kanaoka and Hatanaka for the corresponding solution phase process (49\%). This permitted the solid state reaction to be followed to 100\% conversion by X-ray powder diffractometry, which showed that the process is a single crystal-to-polycrystalline transformation involving a regular and progressive conversion of 1 into 2 with no obvious diffraction peaks that might be attributable to the intermediate cyclobutanol.},
	keywords = {C-H...O, SYSTEMS},
	isbn = {0008-4042},
	url = {<Go to ISI>://A1994PJ99400010},
	author = {Fu, T. Y. and Scheffer, J. R. and Trotter, J.}
}
@article {7276,
	title = {STRUCTURAL STUDIES OF ORGANOBORON COMPOUNDS .56. 1-BENZYL-7-METHYL-3,5-DIPHENYL-2,4,6-TRIOXA-1-AZONIA-3-BORA-5-BORATABICY CLO[3.3.0]OCTANE AND 1,4,6,9-TETRAMETHYL-2,7-DIPHENYL-3,8,11,12-TETRAOXA-1,6-DIAZONIA-2,7-DIB ORATATRICYCLO[5.3.1.1(2,6)]DODECANE},
	journal = {Canadian Journal of Chemistry-Revue Canadienne De Chimie},
	volume = {70},
	number = {11},
	year = {1992},
	note = {ISI Document Delivery No.: KC742Times Cited: 13Cited Reference Count: 31},
	month = {Nov},
	pages = {2809-2817},
	type = {Article},
	abstract = {{The preparation of the N-(2-hydroxypropyl)-N-alkylhydroxylamines, 6a (R = CH3) and 6b (R = CH2Ph), and their reactions with phenylboronic acid are described. Regardless of the molar ratios of reactants employed, the reaction with 6b leads to the 1:2 condensate 1-benzyl-7-methyl-3,5-diphenyl-2,4,6-trioxa-1-azonia-3-bora-5-boratabicy clo[3.3.0]octane, 7, while that with 6a gives rise to the 1:1 condensate 1,4,6,9-tetramethyl-2,7-diphenyl-3,8,11,12-tetraoxa-1,6-diazonia-2,7-dib oratatricyclo[5.3.1.1(2,6)]dodecane, 11 (the cyclic BONBON dimer of 4,6-dimethyl-2-phenyl-1,3-dioxa-4-aza-2-boracyclohexane, 9). Compounds 7 and 11 both crystallize in the triclinic space group P1BAR: for 7; a = 13.126(1)},
	keywords = {C-H...O, CRYSTAL, MOLECULAR-STRUCTURE},
	isbn = {0008-4042},
	url = {<Go to ISI>://A1992KC74200017},
	author = {Kliegel, W. and Lubkowitz, G. and Rettig, S. J. and Trotter, J.}
}
