Potassium allyl derivatives

The electronic spectrum of 1,5-diphenylpentadienyllithium in thf shows the presence of contact (tight) and.solvent-separated (loose) ion pairs. The smaller the cation and the more delocalized the anion, the greater is the tendency to form loose ion pairs. They are also favored as the temperature is lowered (64,65). 13C-NMR studies (66,67) have been interpreted in terms of appreciable covalency, but the present view is that organolithiums are predominantly ionic (68). Schlosser and Stahle have analyzed coupling constants 2J(C—H) and 3J(H—H) in the 13C- and H-NMR spectra of allyl derivatives of Mg, Li, Na, and K and of pentadienyls of Li and K (69). They conclude that considerable pleating of the allyl and pentadienylmetal structures occurs. The ligand is by no means planar, and the metal binds to the electron-rich odd-numbered sites. The lithium is considered to be q3 whereas the potassium is able to reach t]5 coordination with a U-shaped ligand. 

Lewis acids and Bu4NI catalyzed allylboration with potassium allyl- and crotyltrifluoroborates (Equation (154)).30,40 620,621 The reaction of pinacol ester derivatives was very slow even at room temperature, but Sc(OTf)3 smoothly catalyzed the addition at — 78 °C with high diastereoselectivity (Equation (155)622 and (156)623,624). A palladium pincer complex catalyzed the addition of trifluoroborate to tosylimines (Equation (157)).625... 

Allylic potassium organometallics derived from BuLi-r-BuOK react with electrophiles predominantly at the a-position. °... 

D-Glyceraldehyde acetonide (118) has also been used for the synthesis of other (3-lactams (Scheme 14). It was converted into the Schiff base 129, followed by reaction with potassium azidoacetate, cyanuric chloride and triethylamine to give the p-lactam 130 as a single c/s-isomer in 55% yield. The reaction of 130 with methoxyacetyl chloride in the presence of triethylamine afforded the cw-p-lactam 131. Similarly, c/ -p-lactams 131-135 were also prepared as single isomers in comparable yields. Acid hydrolysis of 130 afforded 136, which underwent oxidation of the diol side chain and then removal of the p-methoxybenzyl group with CAN to afford 137. The allyl derivative 135 was oxidized to... 

Methyl 3-C-allyl-4,6-0-benzylidene-3-deoxy-a-D-glucopyranoside has been used as a common starting material for preparing annulated sugars involving intramolecular Homer-Wadsworth-Emmons reactions. Thus successive reaction of the allyl derivative with osmium tetroxide, lithium dimethylmethylphosphonate, Dess-Martin periodane then potassium carbonate furnished 51. Whereas successive reaction of the allyl derivative with borane-THF, PCC oxidation, lithium dimethylmethylphosphonate, Dess-Martin periodane then potassium carbonate afforded 52. Analogous chemistry was also performed on methyl 2-C-allyl-4,6-0-benzylidene-2-deoxy-a-D-allopyranoside. ... 

Potassium tert-butoxide/dimethyl sulfoxide 0-Propenyl from 0-allyl derivatives Allyl as protective group... 

Pd-catalyzed asymmetric allylic alkylation is a typical catalytic carbon-carbon bond forming reaction [ 126 -128]. The Pd-complex of the ligand (R)-3b bearing methyl, 2-biphenyl and cyclohexyl groups as the three substituents attached to the P-chirogenic phosphorus atom was found to be in situ an efficient catalyst in the asymmetric allylic alkylation of l-acetoxy-l,3-diphenylprop-2-en (4) with malonate derivatives in the presence of AT,0-bis(trimethylsilyl)acetamide (BSA) and potassium acetate, affording enantioselectivity up to 96% and quantitative... 

The directive effect of allylic hydroxy groups can be used in conjunction with chiral catalysts to achieve enantioselective cyclopropanation. The chiral ligand used is a boronate ester derived from the (VjA jA N -tetramethyl amide of tartaric acid.186 Similar results are obtained using the potassium alkoxide, again indicating the Lewis base character of the directive effect. 

Cyclization of quinoline derivatives 57 in DMSO under the action of Cs2C03 at 85 °C afforded diesters 49 <1995T11125>. No cyclization product could be obtained when a piperazino group was present in 57 (Rz = piperazino). Cyclization in the presence of NaH gave a lower yield. When the potassium salt of 57 was used in the presence of 20 mol% of Cul, the conversion was almost quantitative, but the removal of the last traces of copper was difficult. When allyl ester 57 (R = Et, R1 = allyl, R2 = 4 - 7/-biu o ycarbonyl-l -pipcridinyl) was cyclized in DMSO in the presence of Cul and KOBuc at 50-55 °C for 0.5 h, then 100-105 °C for 6 h, the 3-ester 50 (R = Et, R1 = 4-tert-butoxycarbonyl-l-piperidinyl) was obtained in 32% yield. 

The enantioselective nitroaldol reaction of phe-nylalaninals 45 with nitromethane was also promoted with the N-anthracenylmethyl ammonium fluorides in the presence of potassium fluoride.1411 Interestingly, as shown in Scheme 16, the major product was the (2R,3S)-isomer 46a when N,N-dibenzyl-(S)-phenylalaninal and 12 (R=benzyl, X=F) were used while the (2S,3S)-isomer 46b was major when N-tert-butoxycarbonyl derivative 45b and 12 (R=allyl, X=Br) together with potassium fluoride were used. The nitroalcohols 46a and 46b were respectively converted to amprenavir 47a, a HIV protease inhibitor, and its diastereomer 47b. The... 

Carbohydrate lactones have been used as the carbonyl reagent in the Reformatsky reaction. Thus, 2,3 5,6-di-O-cyclohexylidene-D-mannono-1,4-lactone [44, obtained by oxidation of the mannofuranose derivative (49)] reacted with ethyl bromoacetate and zinc to give the protected 2-deoxy-3-octulosonic acid ethyl ester (45a) in 69% yield (50). Ketonic hydrolysis with potassium hydroxide in aqueous methanol, followed by acidification and heating, afforded the 1-deoxyheptulose derivative 45b. Similarly, starting from compound 44, the 1-C-substituted allyl and propar-gyl lactols were prepared on reaction with allyl or propaigyl bromides in the presence of zinc (51). 

The reactions of the corresponding propargyl sulfoxides and sulfones now resemble the chemistry of the other acceptor-substituted derivatives such as ketones and aldehydes (see Section 1.2.4). Compared with the thioethers, here much milder bases are sufficient apart from aluminum oxide, often triethylamine or potassium carbonate are used. Sometimes even a spontaneous isomerization takes place. The selective isomerization of one triple bond in the presence of a second triple bond in 126 [313] (Scheme 1.56) or an allyl sulfone in 129 [314] (Scheme 1.57) are just two examples out of a whole series [178, 304, 313, 315-331]. When, on the other hand, the in situ oxidation of 126 was carried out in an aprotic solvent, no isomerization at all was observed. 

The analogue, t-butyl methyl iminodicarboxylate 25, is obtained by the reaction of methanol with t-butyl oxamate (24) in the presence of lead tetraacetate. Its stable non-hygroscopic potassium salt is converted into alkyl derivatives 26 by the action of alkyl halides such as butyl bromide, allyl bromide, propargyl bromide and ethyl bromoacetate. The products are hydrolysed by trifluoroacetic acid to salts of primary amines, whereas... 

Alkylidene cyclohexenes were synthesized stereoselectively from bis-allyl silylketene acetals derived from cyclohexenones93. As shown in equation 66, Ireland Claisen rearrangement of ester 133 gave only E-diene 136. Reaction of 133 with potassium... 

Protected primary allylic amines were generated from allylic carbonates and ammonia equivalents. Iridium-catalyzed allylic substitution has now been reported with sulfonamides [90, 91], imides [89, 91-93], and trifluoroacetamide [89] to form branched, protected, primary allylic amines (Table 5). When tested, yields and selectivities were highest from reactions catalyzed by complexes derived from L2. Reactions of potassium trifluoroacetamide and lithium di-tert-butyhminodi-carboxylate were conducted with catalysts derived from the simplified ligand L7. Reactions of nosylamide and trifluoroacetamide form singly-protected amine products. The other ammonia equivalents lead to the formation of doubly protected allylic amine products, but one protecting group can be removed selectively, except when the product is derived from phthalimide. 

Figure 7. EPR absorption derivative spectra of photoreduced active aconitase. Enzyme ( 5 mg/ml) in 100 mM Hepes, pH 7.5, plus 5 pM deazaflavin and 10 mM potassium oxalate was photoreduced in the presence of either A) 10 mM tricarb-allylate, B) 1 mM citrate, or C) 10 mM rrans-aconitate. The numbers above each spectrum are the g-values of prominent features. Experimental conditions for obtaining EPR spectra were 13 K, 1 milliwatt microwave power, 0.8 mT modulation amplitude, and 9.24 GHz microwave frequency.

The double bond of 9-allylcarbazoles can be moved into conjugation with the nitrogen by treatment with potassium rcrt-butoxide in dimethyl sulfoxide the cis-prop-l-enyl isomers were formed initially in studies with 9-allyl-carbazole, 9-allyl-3-chlorocarbazole, 9-allyl-3-nitrocarbazole, and 9-allyl-3,6-dichlorocarbazole. " Such isomerizations must proceed via a car-banion produced by proton abstraction from the saturated carbon on nitrogen. Indeed, when the red anion from 9-benzylcarbazole, formed using n-butyllithium, was quenched with deuterium oxide, the 9-CHDPh derivative was obtained. When the anions from 9-ally 1-carbazoles in the series 81... 

Similarly, alkylation of the potassium salt of pyrido[3,4- pyridazin-l(277)-one 103 with methyl iodide or allyl bromide gave the N-alkylated derivatives 104 and 105, respectively. On the other hand, benzylation of 103 with benzyl bromide afforded a mixture of A-benzyl 106 and 0-benzyl derivatives 107 (Equation 6) <1996T3261>. 

Yttrium-catalyzed diene cyclization/hydrosilylation was applied to the synthesis of aliphatic nitrogen heterocycles such as the indolizidine alkaloid ( )-epilupinine. l-Allyl-2-vinylpiperidine 30 was synthesized in four steps in 59% overall yield from commercially available ( )-2-piperidinemethanol (Scheme 10). Treatment of 30 with phenylsilane and a catalytic amount of Gp 2YGH3(THF) gave silylated quinolizidine derivative 31 in 84% yield, resulting from selective hydrometallation of the A-allyl G=G bond in preference to the exocyclic vinylic G=G bond. Oxidation of the crude reaction mixture with tert-huVf hydrogen peroxide and potassium hydride gave (i)-epilupinine in 51-62% yield from 30 (Scheme 10). 

Furo[3,2-c][l]benzopyran-4-ones have been prepared either by acid catalyzed condensation of 4-hydroxycoumarin with a benzoin derivative (equation 11) (81IJC(B)614) or from 3-allyl-4-hydroxycoumarins on oxidation with osmium tetroxide/potassium periodate followed by cyclization of the intermediary aldehyde with PPA (equation 12) (79G109). 

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