Reactions involving electron transfer. 11. Reaction of lithium dimethylcuprate with diaryl ketones

House, Herbert O.; Chu, Chia-Yeh

doi:10.1021/jo00881a003

Cited by 40 publications

(25 citation statements)

References 10 publications

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“…For example, the reagent having the stoichiometry LiCuPh2-PhLi appears to be more reactive than LiCuPh2 in metal-halogen exchange reactions and coupling with aryl bromides.2 Also it has been recently found that a 3:2 mixture of LiCufCHsh and CH3L1 is more stereoselective toward 4-tert-butylcyclohexanone than either LiCu(CH3)2 or CH3LL3 In addition, mixtures of Li-Cu(CH3)2 and CH3L1 have been found to react with diaryl ketones as if a reducing agent more powerful than either Li-Cu(CH3)2 or CH3Li were present. 4 These reports suggest that lithium diorganocuprates and organolithium compounds are capable of reacting to form complexes of the type Li2Cu(CH3)3 and Li3Cu(CH3)4• However, previous and natural abundance l3C NMR studies on the system CH3L1-LiCu(CH3)2 in diethyl ether at -60 °C failed to detect the existence of any complexes.4•5 •13 In view of the intense interest in this area and the obvious possibility of the existence of other cuprates in addition to LiCu(CH3)2, we decided to study the 1H NMR of the CH3L1-CH3CU mixture further.…”

mentioning

confidence: 99%

The composition of lithium methylcuprates in ether solvents

Ashby¹,

Watkins²

1977

J. Am. Chem. Soc.

104

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Variable temperature ' H NMR studies on the system CH3Li-CH3Cu in various stoichiometric ratios have been carried out in MezO, Et20, and THF. In Me20 and THF, LiCu2(CH3)3 and LiCu(CH& have been found to exist as pure stoichiometric compounds when the C H~L L C H~C U ratio is 1:2 and ]:I, respectively. When the CH3Li:CHQ ratio is 2:1, Li2Cu(CH3)3 is formed as an equilibrium mixture containing LiCu(CH3)2 and CH3Li. In Et20, evidence is presented to indicate the existence of LizCuj(CH3)5, LiCu(CH&, and Li2Cu(CH3)3. The first two compounds can be prepared stoichiometrically pure. However, the latter compound is part of an equilibrium mixture. The solution composition of these cuprates is presented based on variable temperature NMR and molecular association data.Lithium dialkylcuprates have proven to be very versatile reagents in organic synthesis.' Several recent reports, however, have been concerned with unusual reactivity of reagents prepared by mixing lithium dialkl-or diarylcuprates with the corresponding organolithium compounds. For example, the reagent having the stoichiometry LiCuPhrPhLi appears to be more reactive than LiCuPhz in metal-halogen exchange reactions and coupling with aryl bromides.2 Also it has been recently found that a 3:2 mixture of LiCu(CH3)z and CH3Li is more stereoselective toward 4-tert-butylcyclohexanone than either LiCu(CH3)2 or CH3Li.3 In addition, mixtures of LiCu(CH3)z and CH3Li have been found to react with diary1 ketones as if a reducing agent more powerful than either LiCu(CH3)2 or CH3Li were pre~ent.~ These reports suggest that lithium diorganocuprates and organolithium compounds are capable of reacting to form complexes of the type Li*Cu(CH3)3 and Li$u(CH3)4. However, previous ' H and natural abundance I3C NMR studies on the system CH3Li-LiCu(CH3)2 in diethyl ether at -60 OC failed to detect the existence of any c~m p l e x e s .~~~. '~ In view of the intense interest in this area and the obvious possibility of the existence of other cuprates in addition to LiCu(CH3)2, we decided to study the ' H N M R of the CH,Li-CH,Cu mixture further.Dimethyl ether was chosen as the initial solvent for this study since methyl group exchange rates should be significantly slower in dimethyl ether (owing to its greater basicity) than conventional ether solvents (e.g., diethyl ether). In addition, considerably lower solution temperatures can be reached with dimethyl ether (-136 vs. -100 "C) than with most other ethers. After the studies in dimethyl ether, the cuprates were studied in tetrahydrofuran and then finally in diethyl ether. It was our hope that the results obtained in the more basic solvents, dimethyl ether and THF, could be used to help explain the system in diethyl ether. In addition, various ligands were added to the cuprates in diethyl ether in an effort to clarify the situation in that solvent. Experimental SectionApparatus. Reactions were performed under nitrogen at the bench using Schlenk tube techniques.6 Other manipulations were carried out in a glove box equipped with a recircu...

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confidence: 99%

The composition of lithium methylcuprates in ether solvents

Ashby¹,

Watkins²

1977

J. Am. Chem. Soc.

104

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“…The ester 2 has been claimed already in a patent, but without experimental and analytical data. 15 The methyl ether 3 was obtained in 87% yield by Williamson reaction of 2 with methanol, whereas reaction of 2 with 2propanol afforded a mixture of products. IR spectra of the mixture revealed the absence of carbonyl groups.…”

Section: Resultsmentioning

confidence: 99%

Photoinitiators with functional groups. III. Water‐soluble photoinitiators containing carbohydrate residues

Knaus¹,

Gruber²

1995

J. Polym. Sci. A Polym. Chem.

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SYNOPSISA series of new water-soluble photoinitiators (PIS) for UV curing of water-borne systems was synthesized by covalent bonding of carbohydrate residues such as D-glucose, sucrose, maltose, 1-amino-D-sorbitol and D-gluconicacid-&lactone to the commercially available PI 2-hydroxy-1-[ 4-(2-hydroxy-ethoxy)phenyl] -2-methylpropan-1-one (Darocur 2959) ( 1). In addition, new functional derivatives of 1 containing tosyl-or chloride residues as well as primary or secondary amino groups were prepared. Preliminary photocalorimetric tests of the activity demonstrated excellent efficiencies of the PIS in a commercial water-based acrylate formulation exceeding the photoactivity of the reference PI (1) substantially.CCC osS7-624X/95/060929-11 new water-soluble PIS based on a-hydroxy-alkylphen~nes~~'~.'~ containing carbohydrates as nonionic hydrophilic residues. In addition, results of preliminary tests of the photoactivity of the PIS compared to the basic substances are presented. EXPERIMENTALThe solvents were dried and purified by common methods. 1,2 : 5,6-Di-O-isopropyliden-a-glucofuranose ( 8 ) , l3 glucose pentaacetate ( 11 ) , l4 and maltose octaacetate ( 12) l4 were prepared by known procedures. -sulfonic-acid-2-[ 4-( 2-hydroxy-2- 4-Toluene methyl-1-oxopropyl) -phenoxy]ethylester ( 2)A two-phase mixture consisting of a solution of 20 g (96 mmol) 1 in 200 mL CH2C12,12 g NaOH in 30 mL water, and 1.2 g (3.6 mmol) tetrabutyl ammonium hydrogen sulfate (TBAH) as phase transfer catalyst was stirred at 25°C. A solution of 20 g ( 105 mmol) 4-toluene sulfonylchloride in 50 mL CH2C12 was added slowly and the reaction mixture was stirred for 16 h. The phases were separated and the 929

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“…(R)-(4-Biphenyl)phenylmethanol (2d) [16] Obtained from 4-biphenylylaldehyde (1d) (45 mg, 0.25 mmol) according to the general procedure as a white solid; yield: 57 mg (88%, 0.22 mmol, 98% ee); (R)-(2-Bromophenyl)phenylmethanol (2e) [17] Obtained from 2-bromobenzaldehyde (1e) (29 mL, 0.25 mmol) according to the general procedure as a pale yellow solid; yield: 37 mg (56%, 0.14 mmol, 97% ee); (R)-(2-Methoxyphenyl)phenylmethanol (2f) [18] Obtained from 2-methoxybenzaldehyde (1f) (34 mg, 27 mL, 0. (R)-Mesitylphenylmethanol (2g) [19] Obtained from 2,4,6-trimethylbenzaldehyde (1g) (37 mL, 0.25 mmol) according to the general procedure as a white solid; yield: 48 mg (84%, 0.21 mmol, 91% ee); (S)-2,2-Dimethyl-1-phenyl-1-propanol (2h) [20] Obtained from 2,2-dimethyl-1-propanal (1h) (27 mL, 0.25 mmol) according to the general procedure as a pale white solid; yield: 21 mg (51%, 0. 13 20.3 min (R).…”

Section: General Procedures For the Larger Scale Preparation Of Diarylmentioning

confidence: 99%