Syntheses of 3,7-dimethylpentadecan-2-ols from intermediates formed from co-oligomerisation reactions of butadiene with diethyl malonate and acetaldehyde

The products of the reaction of butadiene with diethyl malonate catalysed by a palladium complex and of butadiene with acetaldehyde catalysed by a nickel(0) complex have been used in two syntheses of 3,7-dimethylpentadecan-2-ol.     

Palladium-catalyzed cycloreduction of 5-allen-1-ynes

The palladium-catalyzed cycloreduction of 5-allen-1-ynes gave the corresponding 1,2-bisalkylidenecyclopentanes in excellent chemoselectivity and chemical yields. Incorporating an electron-withdrawing group at the acetylenic position showed to be better substrates for the present cycloreduction.     

Concise synthesis of dihydrochalcones via palladium-catalyzed coupling of aryl halides and 1-aryl-2-propen-1-ols

An expedient route to substituted dihydrochalcones is reported. The key step is a palladium-assisted arylation of 1-aryl-2-propen-1-ols. This two-step/one-purification process allows the synthesis of a wide range of compounds with original substitution patterns, including polyphenolic derivatives.     

Lipase-Mediated Resolutions of 1-Aryl-3-Buten-1-ols

Racemic mixtures of 1-aryl-3-buten-1-ols were separated with high enantioselectivity by a lipase-mediated acetylation with vinyl acetate. The effects of the nature, position, and spatial requirements of the phenyl-ring substituents on the separation efficacy were investigated.     

Synthesis of tricyclic nitrogen heterocycles by a sequence of palladium-catalyzed N-H and C(sp3)-H arylations

A range of tricyclic nitrogen heterocycles were synthesized in a straightforward and efficient manner via a sequence involving palladium-catalyzed N-arylation and C(sp(3))-H arylation as the key steps. Whereas the C(sp(3))-H arylation furnished fused 6,5,6-membered ring systems efficiently, the formation of the more strained 6,5,5-membered systems proved to be more challenging and required a subtle adjustment of the reaction conditions.     

Synthesis of 1-aryl-5-arylazo-3-phenylsulfonylpyrazol-4-ols from 1-bromo-3-phenylsulfonyl-2-propanone

Treatment of 1-bromo-3-phenylsulfonyl-2-propanone ( 1 ) with arenediazonium chloride gave 1-aryl-5-arylazo-3-phenylsulfonylpyrazol-4-ols 5a-h in 13–48% yields.     

Synthesis of 1-aryl-5-arylazo-3-phenylsulfonylpyrazol-4-ols from 1-chloro-3-phenylsulfonyl-2-propanone

Treatment of 1-chloro-3-phenylsulfonyl-2-propanone (2) with arenediazonium chlorides gave 1-arylhydrazono-3-chloro-1-phenylsulfonyl-2-propanones 4 , which were cyclized in the presence of sodium acetate to 1-aryl-3-phenylsulfonylpyrazol-4-ols 5B. Further treatment of 5B with arenediazonium chlorides yielded 1-aryl-5-arylazo-3-phenylsulfonylpyrazol-4-ols.     

Some properties of 2-alkoxy-1-alken-3-ols

Conclusions The reaction of 2-alkoxyacroleins with Grignard reagent gave some new 2-alkoxy-1-alken-3-ols, which in the presence of p-toluenesulfonic acid are cyclodimerized to 2,3,5,6-tetraalkyl-2,5-dialkoxy-1,4-dioxanes, which tend to cleave ethanol to give 2,3,5,6-tetraalkyl-5-alkoxy-1,4-dioxenes.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 11, pp. 2534–2538, November, 1980.The authors express their gratitude to V. I. Lavrent'ev and V. Yu. Vitkovskii for taking the mass spectra.     

Versatile synthesis of quinoline-3-carboxylic esters and indol-2-acetic esters by palladium-catalyzed carbonylation of 1-(2-aminoaryl)-2-yn-1-ols

1-(2-Aminoaryl)-2-yn-1-ols, easily obtained by the Grignard reaction between 1-(2-aminoaryl)ketones and alkynylmagnesium bromides, were subjected to carbonylative conditions in the presence of the PdI2-KI catalytic system, in the presence and in the absence of an external oxidant. Under oxidative conditions (80 atm of a 4:1 mixture of CO-air, in MeOH as the solvent at 100 degrees C and in the presence of 2 mol % of PdI2 and 20 mol % of KI), 1-(2-aminoaryl)-2-yn-1-ols bearing a primary amino group were selectively converted into quinoline-3-carboxylic esters in fair to good yields [45-70%, based on starting 1-(2-aminoaryl)ketones], ensuing from 6-endo-dig cyclization followed by dehydration and oxidative methoxycarbonylation. On the other hand, indol-2-acetic esters, deriving from 5-exo-dig cyclization followed by dehydrating methoxycarbonylation, were selectively obtained in moderate to good yields [42-88%, based on starting 1-(2-aminoaryl)ketones] under nonoxidative conditions (90 atm of CO, in MeOH as the solvent at 100 degrees C and in the presence of 2 mol % of PdI2 and 20 mol % of KI), in the case of 1-(2-aminoaryl)-2-yn-1-ols bearing either a primary or secondary amino group and substituted with a bulky group on the triple bond.     

Electron impact fragmentations of 1- and 3-aryl-3-buten-1-ols

The electron impact fragmentation of 1- and 3-aryl-3-buten-1-ols show several distinguishing fragmentations. α-Cleavage predominates in the fragmentation of the 1-aryl-3-buten-1-ols to such an extent that molecular ions of only low intensity are observed. The ion resulting from α-cleavage fragments readily with the loss of the ring substituent to the phenyl ion. An intense molecular ion is observed in the 3-aryl series and a loss of 70 u is a major fragmentation in this series. Based on deuterium labeling studies, this unique fragmentation was explained by a hydroxylic hydrogen migration to the ring accompanied by the loss of allene and formaldehyde. Other major fragmentations observed in the 3-aryl series are: a McLafferty-type rearrangement (loss of formaldehyde), loss of 33 u (water + methyl radical), and the loss of 43 u (C₂H₃O and C₃H₇). The proposed mechanisms have been substantiated by deuterium labeling and high resolution mass spectrometry. Substituent effects play a major role in the 3-aryl series, but are insignificant in the 1-aryl series.     

Copper-catalyzed cycloisomerizations of 5-en-1-yn-3-ols

[reaction: see text] The Cu(I)-catalyzed cycloisomerization of tertiary 5-en-1-yn-3-ols with an 1,2-alkyl shift affords stereoselectively tri- and tetracyclic compounds of high molecular complexity. These results are in agreement with a mechanism in which the cyclopropanation precedes the rearrangement.     

An advantageous route to oxcarbazepine (trileptal) based on palladium-catalyzed arylations free of transmetallating agents

[reaction: see text] A new route to oxcarbazepine (Trileptal), the most widely prescribed antiepileptic drug, starting from commercially available 2'-aminoacetophenone and 1,2-dibromobenzene, is reported. The sequentially accomplished key steps are palladium-catalyzed intermolecular alpha-arylation of ketone enolates and intramolecular N-arylation reactions. After several experiments to establish the best conditions for both arylation processes, the target oxcarbazepine is obtained in a satisfactory overall yield, minimizing the number of steps and employing scalable catalytic procedures developed in partially aqueous media.     

Oxygenation of Trimethylsilylallenes Readily Obtainable from Organoboranes. Syntheses of 1-Trimethylsilyl-1-alkyn-3-ones and 1-Trimethylsilyl-1-alkyn-3-ols

Abstract

Recently we have reported that the reaction of sodium methoxide with ate-complexes (1) readily prepared from trimethyl-silylpropargyl phenyl ether and organoboranes gives trimethyl-silylallenes (2) selectively (eq. 1).¹ In an attempt to find a new synthetic application of such silylallenes (2), the oxidation of 2 was examined. Although the usual oxidants such as m-chloro-perbenzoic acid were found to be unsuitable for the oxidation of the silylallenes, it was discovered that 2 was autoxidized at room temperature to propargylic hydroperoxide (3) (eq. 2). For example, the acidified starch-iodine test² strongly suggested the presence of the organic hydroperoxide in the reaction mixture obtained from 1,2-heptadienyltrimethylsilane (2, R=Bu) and oxygen. The hydroperoxide (3, R=Bu) was isolated in a 40% yield by distillation, 45–48 [ddot]C/0.1 mmHg. In the infrared spectrum, the OH stretching frequency appears at 3430 cm^?1 and the C°C at 2180 cm,^?1     

A New and Facile Synthesis of Chroman-3-ols, 3,4-Dihydro-2H-[1]-Benzopyran-3-ols

o-Allyl phenols react with m-chloroperoxybenzoic acid (m-CPBA) in dry chloroform to give chroman-3-ols in a single step in good yields (93–96%).     

Synthesis of 1-alkyl-2-methylazetidin-3-ones and 1-alkyl-2-methylazetidin-3-ols

Several 1-alkyl-2-methylazetidin-3-ones were prepared in good yield by the hydride-induced cyclization of the corresponding β-bromo-α,α-dimethoxyketimines, the resulting 3,3-dimethoxyazetidines being hydrolyzed by acid. Imination of these 1,2-disubstituted azetidin-3-ones, followed by alkylation under kinetic control conditions resulted in regioisomeric mixtures of 2,4- and 2,2-dialkylated compounds. Analytical samples of the major 2,4-disubstituted derivatives were obtained after extensive chromatographic separation. The cis stereochemistry of the major 2,4-dialkylated isomer was demonstrated on the basis of NMR data.     

A catalytic asymmetric approach to C1-chiral 3-methylene-indan-1-ols

A sequential (R)-BINAP·Ag^IF (2,2′-bis(diphenylphosphino)-1,1′-binaphthyl) (6–10 mol %), and (Ph₃P)₂Pd^IICl₂ (bis(triphenylphosphine)palladium(II) dichloride) (2 mol %) catalyzed asymmetric Sakurai–Hosomi–Yamamoto allylation/Mizoroki–Heck reaction that affords C₁-chiral 3-methylene-indan-1-ols with enantiomeric excess (ee) up to 80% is reported. Notably, this protocol allows for the use of various o-substituted benzaldehydes and allyltrimethoxysilane. It was also discovered that the presence of electron-rich groups had no effect on the enantioselectivity of the reaction, whereas electron-withdrawing groups lead to erosion in product ee.