New Friedel-Crafts chemistry. XIX. Cyclialkylations of some phenylalkanols

Abstract

CYCLIALKYLATIONS OF SOME PHENYLALKANOLS 3571 ratio was detected until the amount of olefin exceeded 10%. Above 10% small differences were noted and the values indicated that the cis alcohol (equatorial OH) was being dehydrated a t a faster rate than the trans alcohol.Control Experiment.--The isolated product obtained from the reaction of methylmagnesium bromide (0.1 M ) with 4-t-butylcyclohexanone (Table I) was dissolved in 10 ml of ether and added to dimethylcadmium or dimethylzinc reagents under the conditions previously described for the reaction of in situ reagents with ketone. After hydrolysis arid work-up, percentages obtained by glpc were unchanged within experimental error.Registry methylzinc, 1, methylmagnesium iodide, methylmagnesium bromide, methyllithium, Ac~owledgment,-we thank the Central university Research Fund (University Of New Hampshire) for partial support.Tertiary 3-and 4-phenylalkanols underwent cyclialkylation readily a t room temperature with sulfuric acid to yield the corresponding indans and tetralins. Primary and (ordinary) secondary 3-phenylalkanols did not undergo cyclialkylation even a t high temperature with phosphoric acid; l,3-diphenyl-l-propanol cyclized readily. 3-P14ethyl-3-phenyl-l-butanol was dehydrated (mainly) by phosphoric acid a t 230°, but some cyclialkylation ocwirred. The requirement of a stable secondary or tertiary carbonium-ion intermediate is implied by these results; in the case of the last example, a l13-phenyl shift provides the required intermediate. Some time ago Bogert and ~o w o r k e r s~~~investigated the cyclialkylations of some phenylalkanols and related alkenes. They identified their cyclization products by means of qualitative elemental analyses, comparison of physical constants, and characterization, of oxidation products. Since such identification methods are qualitative a t best and probably liable to failure in detecting minor components, we decided to reinvestigate some of the reported results, applying modern instrumental methods of separation and identification. Some of the experiments are repetitions of cyclialkylations reported previously, 2 , 3 but others are new ones designed to provide more insight into the mechanisms of these reactions. Results and DiscussionThe conditions and results of our cyclization experiments are summarinied in the accompanying Table I. 3-Phenyl-1-propanol (1) and 4-phenyl-1-butanol ( 2 ) were reported by Bogert and Davidson2 to yield polymer and pure tetralin, respectively, upon treatment with phosphoric acid at high temperature. We obtained a product from the former that was shown to contain a trace of indan and a little n-propylbenzene, but the major constituents were the three isomeric phenylpropenes resulting from normal dehydration. Confirmatory evidence for the structure of the latter isomers was obtained by catalytic reduction which converted them to n-propylbenxene, The product from 2 was found to consist of tetralin (80%) and three lower boiling unidentified products (20%).4-Phenyl-2-butanol (3) was report...

Random copolymer of styrene and diene derivatives via anionic living polymerization followed by intramolecular Friedel–Crafts cyclization for high-performance thermoplastics

“…molecular weight compounds via tertiary carbocationic species were also reported in Friedel-Crafts chemistry. 14 The methyl substituent in the isoprene unit would also contribute to more effective cyclization due to the formation of sterically favored 6-endo-trig-like conformation.…”

Modern Friedel–Crafts Chemistry. Part 37. Efficient Syntheses of Some New Julolidines via Cyclialkylations of Heteroaryl Carbinols

“…The procedures described earlier for cyclialkylations of arylalkanols with AlCl 3 /CH 3 NO 2 and PPA were essentially followed. The conditions and yields are shown in Tables and , whereas the physical constants and spectral data of the products 8a , 8b , 8c , 8d , 8e , 8f , 8g , 8h , 8i are given in the following.…”

“…Despite numerous advances in the field of synthetic organic chemistry, the developments of valuable and efficient strategies for the construction of these ring systems remain as a significant challenge. Among these methods, intramolecular Friedel–Crafts cyclialkylations promoted by both Brønsted and Lewis acid catalysts is promising as an efficient method to prepare substituted julolidines.…”

Modern Friedel–Crafts Chemistry. Part 24.† Alkylation of Benzene with 1,2-Dibromo-3-chloro-2-methylpropane in the Presence of Lewis and Brønsted Acid Catalysts‡

“…1 (4) The formation of 6 via intermediates 5 finds analogy in an earlier paper co-authored by one of us. 4 Experimental IR spectra were recorded on a Nicolet Magna 520 FT-IR spectrometer, 1 H NMR spectra were recorded on a Bruker DPX-400 FT-NMR spectrometer, GC-MS data were obtained with a Shimdazu QP-5000 mass spectrometer and microanalyses were performed on a 2400 Perkin Elmer Series 2 CHNS analyser.…”