TY - JOUR
T1 - Barrier to Internal Rotation in 1,2-Bis(bromochloromethyI)-3,4,5,6-tetraisopropyl-benzene
AU - Biali, Silvio E.
AU - Mislow, Kurt
PY - 1988/3/1
Y1 - 1988/3/1
N2 - The tightly gear meshed arrangement of isopropyl and dichloromethyl groups in hexaisopropyl- and hexakis(di-chloromethyl)benzene, respectively, imparts a high barrier to internal rotation. For hexaisopropylbenzene,1 a lower limit of 22 kcal mol-1 was estimated for the topomerization barrier from NMR measurements on a d28 isotopomer and a barrier of ca. 35 kcal mol-1 was calculated by use of the empirical force field (EFF) method. For hexakis(di-chloromethyl) benzene,2 the calculated (EFF) topomerization barrier was 33.9 kcal mol-1. Consistent with these findings is the lower limit of 24 kcal mol?1 estimated (NMR) for the enantiomerization barrier in (1′RS,2′SR)-1,2-bis(l-bromoethyl)-3,4,5,6-tetraisopropyl-benzene.3.
AB - The tightly gear meshed arrangement of isopropyl and dichloromethyl groups in hexaisopropyl- and hexakis(di-chloromethyl)benzene, respectively, imparts a high barrier to internal rotation. For hexaisopropylbenzene,1 a lower limit of 22 kcal mol-1 was estimated for the topomerization barrier from NMR measurements on a d28 isotopomer and a barrier of ca. 35 kcal mol-1 was calculated by use of the empirical force field (EFF) method. For hexakis(di-chloromethyl) benzene,2 the calculated (EFF) topomerization barrier was 33.9 kcal mol-1. Consistent with these findings is the lower limit of 24 kcal mol?1 estimated (NMR) for the enantiomerization barrier in (1′RS,2′SR)-1,2-bis(l-bromoethyl)-3,4,5,6-tetraisopropyl-benzene.3.
UR - http://www.scopus.com/inward/record.url?scp=0011040994&partnerID=8YFLogxK
U2 - 10.1021/jo00241a039
DO - 10.1021/jo00241a039
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AN - SCOPUS:0011040994
SN - 0022-3263
VL - 53
SP - 1318
EP - 1320
JO - Journal of Organic Chemistry
JF - Journal of Organic Chemistry
IS - 6
ER -