From lohl@obelix.uni-muenster.de Tue Jul 19 16:55:01 1994 Received: from obelix.uni-muenster.de for lohl@obelix.uni-muenster.de by www.ccl.net (8.6.9/930601.1506) id QAA09309; Tue, 19 Jul 1994 16:00:51 -0400 Received: from MARTINIQ.UNI-MUENSTER.DE by obelix.uni-muenster.de (AIX 3.2/UCB 5.64/4.03) id AA50093; Tue, 19 Jul 1994 22:01:48 +0200 Received: by martiniq.uni-muenster.de (AIX 3.2/UCB 5.64/4.03) id AA09871; Tue, 19 Jul 1994 22:01:35 +0200 From: lohl@uni-muenster.de Message-Id: <9407192001.AA09871@martiniq.uni-muenster.de> Subject: SUM: radical cyclizations To: chemistry@ccl.net Date: Tue, 19 Jul 1994 22:01:34 +0200 (MES) X-Mailer: ELM [version 2.4 PL23] Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 8bit Content-Length: 6069 Hallo, A few weeks ago I posted a question concering radical cyclization and asked what there is anything known of its calculation. I have been asked to sum it for the others which is what I am doing with pleasure now. I would like to take the chance to say a big 'thank you' to all the contributers. It was a great help for me. The original question was: > For the explanation of experimental data I am interested > in finding the transition states of radical addition or > cyclisation reactions like for example a 6-exo-trig reaction. > Is there anyone aware of recent ab-initio or better semi-empirical > calculations which revealed the TS of any type of a radical addition > or cyclisation? These are the answers: ------------------------ You might want to look at this paper describing a force-field approach to modeling the transitions states of intramolecular cyclization reactions. (Spellmeyer and Houk, J. Org. Chem., 1987, 52(6), 959-974.) The force-field was optimized to produce minima that looked like the transition states of intermolecular radical additions calculated with ab initio methods. The force-field was further optimized to give accurate delta-Es for the regio-selectivity and stereo-selectivity observed in several intramolecular radical cyclization reactions. The accuracy of the model was tested by comparing TSs calculated using ab initio methods (UHF/STO-3G was the highest level we could run at the time) against the "transition states" we calculated using our force-field. They were nearly indistinguishable. These results differed from TSs calculated with MINDO/3, and MNDO. Beckwith and Schiesser have published a different force-field based on intermolecular TSs found using MNDO (Tetrahedron Letts, 1985, 26, 373). I hope this gives you a good place to start. I'd be happy to provide more information if you want. Good luck, David Spellmeyer Chiron Coporation 4560 Horton Street Emeryville, CA 94608 (510)-601-3313 Voice (510)-601-3360 FAX davids@cc.chiron.com e-mail ---------------------------------- Dear Dr.Loehl, I hope the following references on localization of TSs for addition reactions of radicals can be of some help. We are currently studying structure and reactivity of radical cations, but the kind of TSs on which we have long experience are those corresponding to internal migrations and abstraction processes. Anyway, if you have any specific question on metho- dological aspects, we will be pleased of trying to help you. [1] Features of the Potential Energy Surface for Reactions of OH with CH2O M.R.Soto and M.Page J.Phys.Chem., 1990, 94, 3242 [2] Computational Study of Addition and Abstraction Reactions between OH Radical and Dymethyl Sulfide. A Difficult Case. M.L.McKee J.Phys.Chem, 1993, 97, 10971 [3] Computational study of the Addition of OH radical to S=C=S M.L.McKee Chem.Phys.Lett., 1993, 201, 41 [4] Radical Addition to HNO. M.Page and M.R.Soto J.Chem.Phys., 1993, 99, 7709 [5] Addition of O(3P) to CF3O Z.Li and J.S.Francisco Chem.Phys.Lett., 1993, 209, 151 Yours, Laura <<<<<<<<<<<<<<<<<<<<<<<<<>>>>>>>>>>>>>>>>>>>>> ! ! ! Laura Coitino ! ! Universita di Pisa - Dip.to di Chimica e Chim Industriale ! ! Via Risorgimento, 35. I-56100 Pisa, Italy ! ! Phone: Voice (+39-50)-918204 ! ! Fax (+39-50)-502270 ! ! E-mail: laurac@ibm580.icqem.pi.cnr.it ! ! : laurac@ibm540.icqem.pi.cnr.it ! ! ! <<<<<<<<<<<<<<<<<<<<<<<<<>>>>>>>>>>>>>>>>>>>>> ------------------------------------------ I've been doing computations of TS's for the addition of HO an (3P)O to va- rious compounds, mostly by semiempirical methods. Unfortunately I don't have a ref. list handy: what's been published has been in conjunction with exper- iments (silent discharge plasma decomposition). I find that Cl-containing compounds are quite difficult. For CHO compounds, the computations are rather straightforward: start from your product, do a reaction coordinate to sepa- rate it into reagents, pick the highest energy point to optimize to a transi- tion state..... (using keywords like TS in MOPAC--not NEARLY as successful as their writeup would have you believe--SIGMA in AMPAC--another tricky one-- LTRD, POWELL, NLLSQ-also in MOPAC). Do you have access to Chem Abstracts on- line? If so, it shouldn't be hard to do a literature search.... Let me know if you have some more specific questions. I have a lot of computer time avail- able, so could do a bit of trouble-shooting of your inputs. (Right now I have more computer time than my own time, but people have helped me in the past...) Irene Newhouse ----------------------------------------------- It's not a radical reaction, but I published ab initio work on a 6-endo-trig reaction in which focussed on the distortion of the TS due to the cycle. Here is the reference: C.I.Bayly and F.Grein, "Comparison of an intramolecular Michael-type addition to its intermolecular counterpart: an ab initio theoretical study", Canadian Journal of Chemistry, vol. 67, pp. 2137-2177 (1989). Christopher Bayly ------------------------------- Best wishes and thank you very much Thosrten -- |--------------------------------------------------------------------| |Thorsten Loehl Tel.:+49-251/83-3233 | |Inst. f. Organische Chemie Fax : -9772 | |Corrensstr. 40 Email:lohl@uni-muenster.de | |D-48149 Muenster | |Germany | |--------------------------------------------------------------------| From rao@skcla.monsanto.com Tue Jul 19 17:59:13 1994 Received: from tin.monsanto.com for rao@skcla.monsanto.com by www.ccl.net (8.6.9/930601.1506) id RAA10091; Tue, 19 Jul 1994 17:19:26 -0400 Received: from SKCLA.DECnet MAIL11D_V3 by tin.monsanto.com (5.65/Monsanto1.4) id AA07004; Tue, 19 Jul 1994 16:19:13 -0500 Date: Tue, 19 Jul 1994 16:19:12 -0500 Message-Id: <9407192119.AA07004@tin.monsanto.com> From: rao@skcla.monsanto.com (Shashi, Drug Design, K-201/1825 ; 708-982-4545) To: "CHEMISTRY@ccl.net"@TIN.monsanto.com Cc: RAO@ccl.net Subject: Chicago computational chemistry club July 19, 1994 Chicago Computational Chemistry Club (CCCC) Dear CCCC participant, The next seminar talk under the CCCC auspicies will be held on Thursday, the 8th September, 1994 at the Northwestern University campus, as outlined below. Speaker : Peter J. Zielinski Illinois Institute of Technology Title : A New Method for Designing Ligands Venue : Room No. 1358, Tech Building, Department of Physics, Northwestern University, 2145 Sheridan Road, Evanston IL 60208. Pizza and soft drinks will be served from 6:30 - 7:30. Please give us a call or e-mail, if you can make it (Shashi Rao: 708-982-4545, e-mail : rao@skcla.monsanto.com ; Mark Ratner: 708-491-5652 ; e-mail : ratner@mercury.chem.nwu.edu). If you cannot attend, please call anyway to confirm or change your address. Hope to see you again soon. Best wishes, Shashi Rao ====================== The Chicago Computational Chemistry Club Presents Peter J. Zielinski Illinois Institute of Technology A New Method for Designing Ligands Thursday, September 8, 7:30 p.m. Room No. 1358, Tech Building, Department of Physics, Northwestern University, 2145 Sheridan Road, Evanston IL 60208. Abstract: A method for designing ligands based upon the concept of simulated annealing is described. At a given temperature, ligand fragments are randomly selected and placed within a specified region, often replacing existing ligand fragments. For each new ligand fragment combination, bonded and nonbonded energies are compared to those of the previous combination. Acceptance or rejection of the new ligand fragment combination is decided using the Boltzman distribution. Thus, unfavorable fragment switches are sometimes accepted, sacrificing immediate energy gains in an attempt to find fragment combinations with energies approaching the global energy minimum. As temperature is lowered, unfavorable fragment switches become less likely and energetically favorable fragments become increasingly difficult to dislodge. The process is halted when the frequency of switches becomes small. Directions : General (from South) : Take Dempster (East) exit from I-94. Go north (left turn) on Chicago Avenue after you get into Evanston. After a mile or so, Chicago Aveneue will merge with Sheridan Road. Keep to the right lane. The NWU campus containing the Tech bldg is on the right hand side. General (from North) : Take Rt 41 south exit from I-94. Go east (left turn) on Lake avenue. Turn right (south) on Sheridan Road. Follow Sheridan going South till the Noyes street vicinity. The NWU campus containing the Tech bldg is on the left hand side. For more detailed directions to reach Northwestern University and parking information, please contact : Professor Mark Ratner : 708-491-5652 ; e-mail : ratner@mercury.chem.nwu.edu or his secretary : Doreen Kaplan 708-491-2983. From wallyr@netcom.com Tue Jul 19 22:54:46 1994 Received: from netcom.com for wallyr@netcom.com by www.ccl.net (8.6.9/930601.1506) id VAA11522; Tue, 19 Jul 1994 21:56:40 -0400 Received: by netcom.com (8.6.8.1/SMI-4.1/Netcom) id SAA01965; Tue, 19 Jul 1994 18:57:55 -0700 From: wallyr@netcom.com (Walter E. Reiher III) Message-Id: <199407200157.SAA01965@netcom4.netcom.com> Subject: Request info on "QSAR in Environmental Sciences" conference To: chemistry@ccl.net, chminf-l@iubvm.ucs.indiana.edu Date: Tue, 19 Jul 1994 18:57:53 -0700 (PDT) X-Mailer: ELM [version 2.4 PL23] MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Content-Length: 712 Does anyone have information (especially a detailed program) on the upcoming conference "Quantitative Structure-Activity Relationships (QSAR) in Environmental Sciences" in Belgirate, Italy September 13-17? It's not in the OSC Chemistry "conferences" list, and the only announcement I've seen has only an outline of the program and no e-mail addresses. Thanks for your help! Wally ======================================================================== Walter E. Reiher III, Ph.D. WallyR@netcom.com Consultant in Computational Chemistry P.O. Box 61056 voice 408-720-0240 Sunnyvale, CA 94088 fax 408-720-0378