█ _ 0 حصريا كتاب Optional ortho and lateral lithiations of4,4 dimethyl 2 (o tolyl)oxazolines 2024 tolyl)oxazolines: of4,4dimethyl2(otolyl)oxazolines من كتب علمية Optional of 4,4 tolyl)oxazolines Naruki Tahara, Tsutomu Fukuda Masatomo Iwao* Department of Applied Chemistry, Faculty Engineering, Nagasaki University, 1 14 Bunkyo machi, 852 8521, Japan Received 5 September 2002; revised 9 October accepted 11 2002 Abstract—4,4 Dimethyl undergo normal lithiation at the benzylic position by treatment with sec BuLi in diethyl ether −78°C In contrast, metalation with sec TMEDA same temperature leads to 6 Rationalization for unusual is proposed © 2002 Elsevier Science Ltd All rights reserved Directed has been recognized as an excellent method synthesis regiospecifically substituted aromatic compounds The benzene derivatives occurs selectively a directing group (ortho lithiation) However, if methyl group exists directing group, deprotonation proceeds adjacent position preferentially due intrinsic high acidity the benzylic protons (lateral lithiation is especially facile o toluic acid derivatives, such esters, amides, nitriles, oxazolines This may be rationalized additional stabilization of the anion its extended delocalization the carbonyl (or equivalent) moiety lithiation of 4,4 tolyl)oxazoline (1a) been reported Gschwend Hamden 3 We have reinvestigated this reaction discovered very ortholithiation of 1a (Scheme 1) 4 Herein, we report this interesting finding مجاناً PDF اونلاين الطريقة العلمية أو المنهج العلمي الثقافة عبارة عن مجموعة التقنيات والطرق المصممة لفحص الظواهر والمعارف المكتشفة المراقبة حديثا من ضمن محتويات القسم : العلماء , أحيائية, بيئية لا خيالية, رياضيات, طب, علم والكثير