@article {1610,
	title = {Monitoring reaction centers and molecules during an enantioselective photoreaction in a crystal},
	journal = {Crystengcomm},
	volume = {8},
	number = {8},
	year = {2006},
	note = {ISI Document Delivery No.: 071LZTimes Cited: 9Cited Reference Count: 19Turowska-Tyrk, Ilona Bakowicz, Julia Scheffer, John R. Xia, Wujiong},
	pages = {616-621},
	type = {Article},
	abstract = {The single crystal-to-single crystal retro-Claisen photorearrangement of the salt of 7-(4-carboxybenzoyl) norbornene with (S)-(2)-1-cyclohexylethylamine was studied. Although this reaction is an ionic chiral auxiliary-mediated asymmetric synthesis, which normally affords highly enantio-enriched products, the enantiomeric excess in this case is a relatively low 60\% (80\% of one enantiomer, 20\% of the other). X-ray structure analysis was used in order to describe changes in the reaction centers and the behavior of molecules during the photoreaction and to understand the formation of two enantiomers. It was discovered that the conformation of the reactant molecules changes during the photoreaction to one that enables the formation of the minor enantiomer. This was seen clearly at ca. 30\% reaction progress. The variations in the cell constants as a function of reaction progress are also presented. The structural changes taking place during the retro-Claisen photorearrangement are compared to the changes observed for other intra- and intermolecular photoreactions in crystals.},
	keywords = {2-BENZYL-5-BENZYLIDENECYCLOPENTANONE, ASYMMETRIC INDUCTION, PHOTODIMERIZATION, SOLID-STATE, STRUCTURAL TRANSFORMATIONS, Yang photocyclization},
	isbn = {1466-8033},
	url = {<Go to ISI>://000239605000007},
	author = {Turowska-Tyrk, I. and Bakowicz, J. and Scheffer, J. R. and Xia, W. J.}
}
@article {1064,
	title = {Molecular mechanics-assisted crystal engineering of solid state photoreactions: application to the Yang photocyclization of alpha-1-norbornylacetophenone derivatives},
	journal = {Tetrahedron Letters},
	volume = {46},
	number = {7},
	year = {2005},
	note = {ISI Document Delivery No.: 895FRTimes Cited: 3Cited Reference Count: 11},
	month = {Feb},
	pages = {1141-1144},
	type = {Article},
	abstract = {Based on molecular mechanics, Yang photocyclization of alpha-1-norbornylacetophenone derivatives in the crystalline state was engineered through methylation adjacent to the carbonyl group, thus changing the conformation in the crystal and leading to enhanced diastereo- and enantioselectivity. (C) 2004 Elsevier Ltd. All rights reserved.},
	keywords = {ASYMMETRIC INDUCTION, crystal engineering, GEOMETRIC REQUIREMENTS, II REACTION, ionic chiral auxiliaries, REACTIVITY, solid state photochemistry, X-RAY CRYSTALLOGRAPHY, Yang photocyclization},
	isbn = {0040-4039},
	url = {<Go to ISI>://000226846800021},
	author = {Botoshansky, M. and Braga, D. and Kaftory, M. and Maini, L. and Patrick, B. O. and Scheffer, J. R. and Wang, K. Y.}
}
@article {4505,
	title = {An ionic chiral auxiliary-induced regioselective and enantioselective Yang photocyclization reaction in the crystalline state},
	journal = {Tetrahedron Letters},
	volume = {40},
	number = {50},
	year = {1999},
	note = {ISI Document Delivery No.: 258FJTimes Cited: 16Cited Reference Count: 19},
	month = {Dec},
	pages = {8729-8732},
	type = {Article},
	abstract = {cis-9-Decalyl aryl ketones undergo Yang photocyclization in solution to afford an approximately 1:1 mixture of two regioisomeric racemic cyclobutanols. In contrast, irradiation in the crystalline state in the presence of various ionic chiral auxiliaries leads to a single cyclobutanol in >98\% enantiomeric excess. X-Ray crystallography reveals the source of the regio-, diastereo- and enantioselectivity. (C) 1999 Elsevier Science Ltd. All rights reserved.},
	keywords = {ASYMMETRIC INDUCTION, CARBOXYLATE, KETONES, ORGANIC-PHOTOCHEMISTRY, PHOTOCHEMISTRY, SOLID-STATE, Yang photocyclization},
	isbn = {0040-4039},
	url = {<Go to ISI>://000083827200003},
	author = {Cheung, E. and Kang, T. and Raymond, J. R. and Scheffer, J. R. and Trotter, J.}
}
@article {4505,
	title = {An ionic chiral auxiliary-induced regioselective and enantioselective Yang photocyclization reaction in the crystalline state},
	journal = {Tetrahedron Letters},
	volume = {40},
	number = {50},
	year = {1999},
	note = {ISI Document Delivery No.: 258FJTimes Cited: 16Cited Reference Count: 19},
	month = {Dec},
	pages = {8729-8732},
	type = {Article},
	abstract = {cis-9-Decalyl aryl ketones undergo Yang photocyclization in solution to afford an approximately 1:1 mixture of two regioisomeric racemic cyclobutanols. In contrast, irradiation in the crystalline state in the presence of various ionic chiral auxiliaries leads to a single cyclobutanol in >98\% enantiomeric excess. X-Ray crystallography reveals the source of the regio-, diastereo- and enantioselectivity. (C) 1999 Elsevier Science Ltd. All rights reserved.},
	keywords = {ASYMMETRIC INDUCTION, CARBOXYLATE, KETONES, ORGANIC-PHOTOCHEMISTRY, PHOTOCHEMISTRY, SOLID-STATE, Yang photocyclization},
	isbn = {0040-4039},
	url = {<Go to ISI>://000083827200003},
	author = {Cheung, E. and Kang, T. and Raymond, J. R. and Scheffer, J. R. and Trotter, J.}
}
