Synthesis and Synthetic Utilization of alpha-Functionalized Vinylphosphonates Bearing beta-Oxy or beta-Thio Substituents

Copper-Catalyzed Enaminone C(sp2)-N Bond Phosphonation for Stereoselective Synthesis of Alkenylphosphonates

A direct enaminone C-N bond coupling functionalization that generates a new C-P bond using dialkyl phosphonate for the efficient and stereoselective synthesis of (E)-alkenylphosphonates is reported. The reactions toward target products proceed well with a broad scope, disclosing a valuable new synthetic application of enaminones by the interesting C(sp²)-N bond elaboration.

Regioselective synthesis of isoxazole and 1,2,4-oxadiazole-derived phosphonates via [3 + 2] cycloaddition

The regioselective synthesis of 3,4- and 3,5-disubstituted izoxazole- and 1,2,4-oxadiazole-derived phosphonates is described, including analogues of phosphohistidine.

Crystal structure of ethyl 2-cyano-2-(1,3-di-thian-2-yl-idene)acetate

The title compound, C9H11NO2S2, contains a 1,3-di-thiane ring which has a twist-boat conformation. The dihedral angle between the mean planes of the ethyl acetate group and the di-thiane ring is 17.56 (13)°. In the crystal, mol-ecules stack in layers up the a-axis direction, however, there are no significant inter-molecular inter-actions present.

Recent developments of ketene dithioacetal chemistry

Ketene dithioacetals are versatile intermediates in organic synthesis. Extensive research, since the last decade, has given rise to new prospects in their chemistry. The objective of this review is twofold: first, to highlight the new prospects in the chemistry of functionalized ketene dithioacetals, and second, to provide an intrinsic link between ketene dithioacetal groups and a variety of other functional groups, which has brought out many new facts that will assist in future designs.

Four-Component Reaction between Trimethyl Phosphite, Aroyl Chlorides and Dialkyl Acetylenedicarboxylate with Benzoic Acid Hydrazide

A four-component and one-pot reaction between trimethyl phosphite, a dialkyl acetylene dicarboxylate and an aroyl chloride with benzoic acid hydrazide is described as a simple and efficient route for the synthesis of functionalised pyrazoles in good yields.

A one-pot Synthesis of (E,E)-1-arylseleno-substituted 1,5-dien-3-ynes by Palladium-Catalysed Three Component Cross-Coupling Reaction

( E,E)-1-Arylseleno-substituted 1,5-dien-3-ynes can be stereoselectively synthesised in one pot, in good yields with high stereoselectivity, by the Pd(PPh3)4-catalysed Stille coupling of ( E)-1-iodo-2-arylselenoethenes with trimethyl-stannyl(trimethylsilyl)ethyne, followed by the cross-coupling with ( E)-vinyl iodides in the presence of tris(diethylamino) sulfonium trimethyldifluorosilicate (TASF).

A Facile Stereoselective Synthesis of (Z)-2-ethoxycarbonyl-substituted 1,3-enynes from (E)-α-stannyl-α,β-unsaturated esters and alkynyl bromides

Palladium-catalysed hydrostannylation of alkynyl esters in benzene at room temperature gives regio- and stereoselectively ( E)-α-stannyl-α,β-unsaturated esters in good yields. ( E)-α-Stannyl-α,β-unsaturated ethyl esters are difunctional group reagents which undergo Stille coupling reactions with alkynyl bromides in the presence of Pd(PPh3)4 and Cul co-catalyst to afford stereoselectively ( Z)-2-ethoxycarbonyl-substituted 1,3-enynes in good yields.

Novel three-component route to diastereoselective synthesis of trisubstituted vinylphosphonates using phosphites, acetylenic esters, and aroyl chlorides

Trisubstituted vinylphosphonates have been prepared via three-component reaction using phosphites, acetylenic esters, and aroyl chlorides in good yields. A variety of phosphites, activated acetylenes, and aroyl chlorides have been successfully employed in these reactions. In addition, three-component synthesis of vinylphosphonate provides exclusive E-olefin stereochemistry.

Stereoselective Synthesis of (E,E)-1-Arylseleno-Substituted 1,5-Dien-3-Ynes

Sonogashira coupling of (E)-1-iodo-2-arylselenoethylenes 1 with (trimethylsilyl)acetylene gave (E)-1-arylseleno-4-(trimethylsilyl)but-1-en-3-ynes 2, which underwent desilylation to afford (E)-1-arylselenobut-1-en-3-ynes 3 in high yields. (E,E)-1-Arylseleno-substituted 1,5-dien-3-ynes 5 could be synthesised stereoselectively via Sonogashira coupling of (E)-1-arylselenobut-1-en-3-ynes 3 with (E)-vinyl iodides 4.

Generation of α-phosphonovinyl radicals and development of a new route to highly functionalized vinylphosphonates and vinylphosphonate-incorporated carbocyclic or heterocyclic compounds via a radical trapping sequence

The first direct generation of synthetically useful alpha-phosphonovinyl radicals was achieved by treatment of alpha-phosphonovinyl halides with a tributyltin radical. The alpha-phosphonovinyl radicals 2a-d were trapped with electron-rich olefins and an electron-deficient olefin to produce alpha-functionalized vinylphosphonates 3a-f in 16-55% yields. The alpha-phosphonovinyl radicals 7e-g containing the YCH2CH=CH2 (Y = O, CH2, S) substituent at the beta-position afforded mixtures of 5-exo and 6-endo cyclization products, 5e-g and 6e-g, in good yields. The 5-exo/6-endo product ratios increase in the following order of the beta-substituent: OCH2CH=CH2 > CH2CH2CH=CH2 > SCH2CH=CH2. The effects of the beta-substituents upon the cyclization reaction were discussed. Radical cyclization of alpha-phosphonovinyl radicals bearing functional groups such as geranyloxy, geranylthio, and (2-cyclohexen-1-yl)thio groups at the beta-position afforded 5-exo, 5-exo and 6-endo, and cis-fused-5,6-ring cyclization products incorporating an alpha,beta-unsaturated phosphonate unit within the ring, respectively, in good yields. The alpha-phosphonovinyl radical 20 underwent tandem radical cyclization-radical cyclization to produce a mixture of two isomeric bicyclo[4.3.0]nonenes including a vinylphosphonate moiety in high yield.

Coupling reactions of alpha-bromoalkenyl phosphonates with aryl boronic acids and alkenyl borates

[reaction: see text] Transition metal-catalyzed arylation and alkenylation of the alpha-bromoalkenyl phosphonates were investigated with organoboranes and -borates. Arylation was successful with the aryl boronic acids and a palladium catalyst, while alkenylation was found to proceed with alkenyl borates and a nickel catalyst. In addition, an intramolecular Diels-Alder reaction of the diene prepared by the alkenylation afforded the corresponding adduct.

Carbon-carbon bond formation of alkenylphosphonates by aldehyde insertion into zirconacycle phosphonates

Ethyl 1-butynylphosphonate reacts with Cp(2)ZrCl(2)/2n-BuLi to give a three-membered zirconacycle that readily inserts aldehydes. Hydrolysis of the intermediate five-membered zirconacycles leads to two products, 4 and 5. In the major product, 5, the aldehyde inserts into C2 of the zirconacycle, while in the minor product, 4, the aldehyde inserts into C1. Products 5 are obtained in 38-75% isolated yields. Products 4 are obtained in approximately 1-12%. Essentially, only compounds 5 are produced with ortho-substituted aldehydes. The regio- and stereochemistry of 4 and 5 were determined by (3)J(PH), (2)J(PC2), and (3)J(PC3) coupling constants.

Lewis Acid-Promoted Deoxygenative Di[β,β-bis(ethylthio)]vinylation of Aldehydes with Trimethylsilylketene Bis(ethylthio)acetal

Silylketene dithioacetal 1 reacted with aldehydes 2a-o, 14, or cinnamaldehyde (11) in the presence of Lewis acid to give deoxygenative divinylation products, 3-substituted 1,4-pentadienes 3a-o, 15, or 5-phenyl-1,3,6-heptatriene 13b, in good to moderate yields. Similar reaction with 2-aminobenzaldehyde (16) or salicylaldehyde (17) produced quinoline 19 or chroman 20 in 40-58% yield. Treatment of 1 with alpha-diketones 22a-c or alpha-ketoester 24 led to tetrasubstituted furans 23a-c or allylic alcohol 25, respectively, in rather low yields. The formation mechanisms of these products are discussed.

cis-Vinylphosphonates and 1,3-Butadienylphosphonates by Zirconation of 1-Alkynylphosphonates

[structure in text] Addition of "zirconocene" to 1-alkynylphosphonates gives three-membered zirconacylces that can be hydrolyzed to cis-vinylphosphonates or further reacted with alkynes/hydrolysis to give substituted (Z,E)- and (E,E)-1,3-butadienylphosphonates.

Synthesis and Synthetic Application of alpha-Formylvinylphosphonates. Facile Synthesis of Phosphono-Substituted Heterocyclic Compounds

The beta-ethoxy-alpha-phosphonovinyl anion, generated from beta-(ethoxy)vinylphosphonate 1 and LDA, reacted with aldehydes and ketones or phenyl isocyanate to give the corresponding allylic alcohols 2a-m or 1,3-diphenyl-5-phosphonouracil 4 in good or moderate yields. Treatment of the alcohols 2a-d,g,h,j with trifluoroacetic acid led to alpha-formylvinylphosphonates 5a-d,g,h,j in excellent yields. Synthetic application of the alpha-formylvinylphosphonates 5a-d,g,h to phosphono-substituted heterocyclic compounds was studied.