Deprotonation/alkylation reactions of monoalkyl-9,10-dihydroanthracenes and -7,12-dihydropleiadenes. Stereochemical outcome and anion models

Abstract

Detection and Isolation of 30I and 7 during the Solvolysis of 3 in pH 7.00 0.2 M Phosphate Buffer. A solution of 50 mg (0.148 mmol) of 3-HBr in 60 mb of pH 7.00 0.20 M phosphate buffer (µ = 1.0, KC1) was prepared under strictly anaerobic conditions and then stirred for 1.5 h at 30 °C. Opening of the reaction to the air was followed by extraction 5x with 50-mL portions of chloroform. These extracts were dried over MgS04, filtered, and concentrated to afford a green-yellow solid, 6.6-mg yield. TLC in 10% ethanol in chloroform indicated 7 as the major product with a trace amount of 30x-Thus, the crude product represents ~25% yield based on 3-HBr. Separation of the two quiñones was carried out by using a 25-g silica gel column prepared with chloroform. Elution with chloroform removed 30I followed

Nucleophilic Dearomatizing (DNAr) Reactions of Aromatic C,H-Systems. A Mature Paradigm in Organic Synthesis

“…Hence, boat-to-boat equilibrium is not a necessary condition to account for the stereochemistry of these reactions. Similar conclusions were obtained through 13 C NMR spectroscopy in the analysis of the alkylation of anions 14 . As mentioned above, the possible role of an electron-transfer mechanism cannot be excluded.…”

“…Similar conclusions were obtained through 13 C NMR spectroscopy in the analysis of the alkylation of anions 14. 71 As mentioned above, the possible role of an electron-transfer mechanism cannot be excluded. It is known that HMPA favors one-electron reduction of anthracene by alkyl-lithiums.…”

1,4‐Dehydrogenation with a Two‐Coordinate Cyclic (Alkyl)(amino)silylene

“…The reaction of CAASi 1 with 9,10-dialkylanthracenes 4e and 4f successfully yielded the correspondinga nthracenes 5e and 5f along with the dihydridosilane 2,h owever,w ith larged iscrepancies between the yields of the resulting anthracene derivatives and 2: [12,13] Whereas the yields of 2 in the reactions of 4e and 4f were6 3a nd 49 %, respectively,t he yields of the an-Scheme2.Dehydrogenation of CHD and DHA with CAASi 1 (Ad = 1-adamantyl). The yields were determined by 1 HNMR spectroscopy.…”

“…Boron tribromide in hexane solution, 1,4‐cyclohexadiene, 9,10‐dihydroacridine, 9,10‐dihydroanthracene, 1,4‐dihydronaphthalene, 9,10‐dimethylanthracene, di‐ tert ‐butyl peroxide, ethanol, ferrocene, 10 % Pd/C, phenol, sodium borodeuteride, and 1,3,5‐tri‐ tert ‐butylbenzene were commercially available and used without further purification. N ‐(1‐Adamantyl)‐3,3‐bis(trimethylsilyl)‐1‐aza‐2‐silacyclopentane‐2,2‐diyl [cyclic (alkyl)(amino)silylene (CAASi), 1 ], 1‐heptadecylcyclohexa‐1,4‐diene, 1‐( tert ‐butyl)‐4‐methoxycyclohexa‐1,4‐diene, 2,3,4,7‐tetrahydro‐1 H ‐indene, 9,10‐dimethyl‐9,10‐dihydroanthracene, 9‐ethyl‐10‐methyl‐9,10‐dihydroanthracene, 9‐isopropyl‐10‐methyl‐9,10‐dihydroanthracene, and 1,4‐dibutyl‐2,3‐bis(methoxycarbonyl)‐9,10‐dihydroanthracene were prepared according to published procedures. H 2 gas was prepared by using a YMC hydrogen generator (YH‐500) and preserved in a YMC MH canister (YMH‐60LP) prior to use.…”

New Modes of Reactivity in the Threshold of the Reduction Potential in Solution. Alkylation of Lithium PAH (Polycyclic Aromatic Hydrocarbon) Dianions by Primary Fluoroalkanes: A Reaction Pathway Complementing the Classical Birch Reductive Alkylation

“…[30] As in the case for Li 2 -3, the reaction of Li 2 -4 with nfluoroA C H T U N G T R E N N U N G octane in THP at 0 8C affords a separable mixture of both the mono-and the dialkylated species 4 a and 4 b in 93 % overall yield ( 4). Assignment of the cis stereochemistry of the dialkylated product 4 b was done on the basis that a cis geometry is obtained by alkylation of the 9-alkyl-9,10-dihydroanthracen-10-yl lithium, [31] and it was confirmed by comparison of the NMR chemical shifts with the cis and trans-9,10-diethyl-9,10-dihydroanthracene. [32] Fluoranthene dianion: Fluoranthene (C 16 H 10 …”