Heptane Derivatives Research Articles

New C-substituted (1S,4S)-2,5-diazabicyclo[2.2.1]heptane derivatives. Preparation utilizing the directed metalation strategy. Application in enantioselective catalysis

New C-substituted derivatives of (1S,4S)-2-methyl-2,5-diazabicyclo[2.2.1]heptane were synthesized utilizing the directed metalation strategy. The absolute configuration of the 3substituted derivative rests on the comparison of the NMR spectra with a product of proven configurational assignment by X-ray crystallographic analysis.

ChemInform Abstract: Synthesis of N‐Heteroaryl‐7‐azabicyclo[2.2.1]heptane Derivatives via Palladium—Bisimidazol‐2‐ylidene Complex Catalyzed Amination Reactions.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform Abstract: Regioselective Cleavage of the Cyclic Ethereal Bond of 7‐Oxabicyclo[2.2.1]heptane Derivatives Mediated by Samarium(II) Iodide.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Optically Active Mesogenic Dispiro[2.0.2.1]Heptane Derivatives and their Unusual Physical Properties

Physical properties, i.e. phase transition temperatures, response times, Ps values, tilt angles, helical twisting powers and helical twisting senses of a series of novel ferroelectric liquid crystalline compounds with non-substituted and halogen-substituted dispiro[2.0.2.1]heptyl moieties in their side chains have been measured. When mixed with an achiral SmC base mixture, the resulting SmC* mixtures containing the novel compounds showed ferroelectricity, and the novel compounds were estimated as useful dopants for ferroelectric liquid crystal mixtures. Further unusual properties were observed with the combinations of the two diastereomeric novel compounds, for example (1S,3R,4S)-4a and (1S,3R,4R)-5a. They showed opposite signs for the Ps and the same sense for the N* helical twisting, which clearly suggests that the direction of the Ps and helical sense of N* must be derived from different origins.

High-Pressure-Promoted Diels−Alder Reactions between Cycloalkenones and 3-Methylsulfanylfuran and 3-Phenylsulfanylfuran

3-Methylsulfanylfuran and 3-phenylsulfanylfuran were found to undergo facile, regioselective and stereoselective Diels−Alder (DA) cycloaddition to a variety of cycloalkenones under high pressure to give the corresponding ring-annulated 7-oxabicyclo[2.2.1]heptene derivatives in good yields. The vinyl sulfide groups in the adducts were oxidized to relatively stable vinylsulfones, which were utilized for synthetic transformations such as further DA cycloadditions and epoxidation.

Regioselective cleavage of the cyclic ethereal bond of 7-oxabicyclo[2.2.1]heptane derivatives mediated by samarium(II) iodide

It was established that exclusively high regioselective CO bond cleavage of 7-oxabicyclo[2.2.1]heptane skeletons, which are unique Diels–Alder products of furans, under mild conditions using samarium(II) iodide and samarium powder yields cyclohexanol derivatives or aromatic compounds.

Titanocene(II)-promoted reaction of gem-dihalides possessing a terminal double bond. New intramolecular cyclopropanation

The Cp 2Ti[P(OEt) 3] 2 1 -promoted intramolecular reaction of gem-dihalides possessing a terminal double bond is described. The treatment of 6,6- and 7,7-dihalo-1-alkenes with 1 produced bicyclo[3.1.0]hexane and bicyclo[4.1.0]heptane derivatives, respectively.

The 1,3-dipolar Cycloaddition of Ethyl N-(ethoxycarbonylmethyl)benzimidate with N-aryl maleimides

1,3-Dipolar cycloaddition of ethyl N-(ethoxycarbonylmethyl)benzimidate (1) with N-aryl maleimides (2) gave a pair of pyrrolo[3,4- c]pyrrole isomers (3, 4) and a 7-azabicyclo[2.2.1]heptane derivative (5). The configuration of isomers 3 and 4 was confirmed by 1H-NMR.

Preparation of highly substituted 7-oxa-1-azabicyclo[2.2.1]heptanes from 4-nitro-1-butene derivatives. Route to polysubstituted piperidines

4-Nitro-1-butene derivatives 2 readily available from the palladium(0)-catalyzed C-allylation of nitroalkanes were converted into highly substituted 7-oxa-1-azabicyclo[2.2.1]heptane derivatives 6 in three steps including an intramolecular 1,3-dipolar cycloaddition reaction. Catalytic hydrogenolysis of the N–O bond in 6 afforded polysubstituted 4-hydroxypiperidines.

ChemInform Abstract: The Unexpected Formation of Bicyclo[2.2.1]heptane Derivatives by Lewis Acid Catalyzed Transannular Double Cyclization.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Asymmetric synthesis of novel polyhydroxylated derivatives of indolizidine and quinolizidine by intramolecular 1,3-dipolar cycloaddition of N-(3-alkenyl)nitrones

Reaction of 3-O-benzyl-1,2-O-isopropylidene-1,5-pentadialdo-α- D-xylofuranose with N-(1,1-dimethylbut-3-enyl)hydroxylamine followed by intramolecular 1,3-dipolar cycloaddition yields 7-oxa-1-azabicyclo[2.2.1]heptane derivative 4, which is easily converted into novel polyhydroxylated quinolizidine 6 and indolizidine 8.

Synthesis and Properties of Optically Active Dispiro[2.0.2.1]heptane Derivatives as Novel Ferroelectric Liquid Crystalline Compounds

Enantioselective enzymatic acylation, using Lipase PS® (Pseudomonas sp., immobilized on Celite, Amano Pharmaceutical Co., Ltd.), of endo-dihalosubstituted and nonsubstituted dispiro[2.0.2.1]heptylmethanol and endo-4-methylenespiropentylmethanol provided the corresponding optically active compounds in high enantiomeric excesses (> 95% ee). Difluorocarbene addition onto the optically active endo-4-methylenespiropentylmethanol yielded the first enantiomerically pure difluorodispiro[2.0.2.1]heptylmethanols. The obtained optically active dispiro[2.0.2.1]heptane derivatives were used in syntheses of phenylpyrimidine derivatives, providing novel ferroelectric liquid crystalline compounds with unique physical properties.

Evidence of Formation of anexo-π-Allyl Complex Intermediate in the Pd0-Catalyzed Alkylation of a Bicyclic Allylic Diacetate with Stabilized Carbon Nucleophiles

The palladium(0)-catalyzed alkylation of 2,3-bis(acetoxymethyl)bicyclo[2.2.1]hepta-2,5-diene 1 with malonate-type enolates as nucleophiles is investigated. A monoalkylated product is formed first, and undergoes (depending on the nucleophile used) a second intramolecular reaction leading to spirocyclopropane-annulated bicyclo[2.2.1]heptene derivatives 5. The formation of endo spirobicyclic cyclopropanes adducts as major isomer is rationalized by assuming formation of an intermediate exo-(π-allyl)palladium complex.

2-Aza [2,2,1] Bicyclo Heptane Derivatives: Ring Expansion, Fragmentation and Synthesis of a Potential TxA2 antagonist

The synthesis of N-tosyl 2-aza [2,2,1] bicycloheptane substituted in 3-position by the α-chain of prostaglandins is described. This synthesis allowed the observation of two valuable transformations of the bicyclic framework: a ring expansion to a 2-aza [3,2,1] bicyclooctane derivative and a fragmentation to cis-1,3 disubstituted cyclopentyl amines.

The unexpected formation of bicyclo[2.2.1]heptane derivatives by Lewis acid-catalyzed transannular double cyclization

Attempted synthesis of the cyclooctanoid skeleton of taxane molecules, by an intramolecular Lewis acid catalyzed Hosomi–Sakurai cyclization of the allylsilane with the aldehyde moiety in 17, unexpectedly led to the formation of bicyclo[2.2.1]heptane derivatives 18 and 19a. Since the formation of spiro compounds by allylsilane terminated domino reaction has no precedent in literature, we extended the reaction conditions to unactivated olefins. Spontaneous aromatization accompanied by bicyclic ring formation was observed in these cases. Bicyclo[2.2.1]heptane derivative 11 was also formed in high yield by an intramolecular SmI2 mediated ketyl–olefin coupling of aldehyde in the hydroxysulfone 10.

An unusual oxidative rearrangement of azabicyclo[2.2.1]heptenes, providing a stereoselective route to 2′- and 3′-hydroxycyclopentylglycines

Treatment of the azabicyclo[2.2.1]heptene derivative 4 with mCPBA for 3–5 seconds generates the oxazabicyclo[3.2.1]octene derivative 7 (X-ray structure) via rapid Meisenheimer rearrangement of the N-oxide 5, whilst heating 7 in MeCN for 4–6 h leads to further rearrangement to the more thermodynamically stable oxazabicyclo[3.3.0]octene isomer 6; 6 and 7 can be readily reduced to enantio-pure hydroxylated cyclopentylglycine derivatives.

A variety of products from a “simple” reaction of [1-(6-acetyl-2-naphthyl)piperidin-4-yl]methyl 4-methylbenzenesulfonate with nucleophiles in DMF–K2CO3

The course of the reaction between [1-(6-acetyl-2-naphthyl)piperidin-4-yl]methyl 4-methylbenzenesulfonate (1) and pyrrolidine, a model nucleophile, in DMF in the presence of anhydrous potassium carbonate at ambient and elevated temperatures is investigated. At elevated temperatures a 1-azabicyclo[2.2.1]heptane derivative is identified as the intermediate in the piperidine-to-pyrrolidine ring contraction process. The formation of formate, carbamate, and hydroxy derivatives, as a consequence of DMF and K2CO3 participating in the reaction, is documented.

Application of an organozinc reagent derived from ( S)-pyroglutamic acid: a formal synthesis of epibatidine

A formal total synthesis of natural (−)-epibatidine has been developed. Key steps in the synthesis are a copper(I)-mediated coupling of an ( S)-pyroglutamic acid-derived organozinc reagent with 1-iodo-3-trimethylsilyl-1-propyne and an N-acyl- or N-sulfonyliminium ion cyclization. Following this route, various N-protected hydroxylactams were converted into 7-azabicylo[2.2.1]heptane derivatives.

Metal-catalysed reactions of β-dicarbonyl compounds with fumaronitrile

β-Dicarbonyl derivatives 1a–f react with fumaronitrile in the presence of catalytic amounts of [Ni(acac) 2] or Ni(OAc) 2 to give 7-oxa-bicyclo[2,2,1]heptene derivatives 3a–f, while in similar experimental conditions, methyl malonate 1g affords the enaminodiester 5.

A new synthetic route for construction of the core of zaragozic acids

A new synthetic route for construction of the core moiety of zaragozic acids from 2,5-furandimethanol ( 2) is described. This synthesis involves highly stereocontrolled transformation of 2 into 7-oxabicyclo[2.2.1]heptane derivative 13, and the Grob fragmentation-reduction-iodo acetalization reaction (one-pot process) of 13 as a key step to give 16.