Synthesis of acetylenedicarboxylic acid esters and asymmetric Diels–Alder reactions of the bis(methyl (<i>S</i>)-lactyl) ester

Charlton, James L.; Chee, Gaik‐Lean; McColeman, Heather

doi:10.1139/v95-180

Cited by 18 publications

(19 citation statements)

References 24 publications

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“…As one can see from Table 2 (entries 1-4), an increase in the phosphine concentration does not significantly effect the yield of the desired product 8. According to recent reports, the electron rich and sterically hindered phosphines 11-14 greatly increase the rate of oxidative addition of vinylic and aryl halides to palladium(0) and prevent undesired hel la ti on.^ According to our results, phosphine 12 gives the best results with both Pd(0Ac)z and Pd(dba)2 (entries 6 and 10). We have also found that Pd(dba)z works better than Pd(0Ac)z for most of the studied phosphines (entries 5-8 versus entries 9-12).…”

Section: Resultssupporting

confidence: 66%

Synthesis of Dihydrobenzofurans via Palladium-Catalyzed Heteroannulations

Rozhkov

2004

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Section: Resultssupporting

confidence: 66%

Synthesis of Dihydrobenzofurans via Palladium-Catalyzed Heteroannulations

Rozhkov

2004

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“…Synthesis of Type 2 electron‐deficient acetylenedicarboxylates 11a–d was not a trivial task: Fischer esterifications, triazine, and carbodiimide couplings were unsuccessful, largely due to competing intramolecular Michael additions to the activated acetylenedicarboxylate intermediates . Modification of a synthetic strategy involving the protection of the electron‐poor alkyne and subsequent acid chloride formation proved successful in furnishing Type 2 alkynes (Sch. 4).…”

Section: Resultsmentioning

confidence: 99%

Nonmigratory internal plasticization of poly(vinyl chloride) via pendant triazoles bearing alkyl or polyether esters

Higa

Tek

Wojtecki

et al. 2018

J. Polym. Sci. Part A: Polym. Chem.

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Branched and linear nonmigratory internal plasticizers attached to PVC by a pendant triazole linkage were synthesized and investigated. Copper‐free azide‐alkyne thermal cycloaddition was employed to covalently bind triazole‐based phthalate mimics to PVC. To systematically investigate the effect of plasticizer structure on glass transition temperature, several architectural motifs were explored. Free volume theory was considered when designing many of these internal plasticizers: hexyl‐tethers were utilized to generate additional space between the triazole‐phthalate mimic and the polymer backbone. Miscibility of these triazole‐plasticizers in PVC is important: variation of the ester moieties on the triazole possessing alkyl and/or poly(ethylene oxide) chains produced a wide range of glass transition temperatures (Tg): from anti‐plasticizing 96 °C, to highly efficient plasticized materials exhibiting Tg values as low as −42 °C. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018, 56, 2397–2411

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“…Bromination of dicyclopropylmethanol [14] with PBr 3 , followed by 1,8-diazabicyclo [5.4.0]undec-7-ene (DBU)-induced HBr elimination provided a 5 : 1 mixture of (E)-and (Z)-1-cyclopropylbutadienes 1j. Wittig olefination of (E)-cinnamaldehyde produced pure (E)-1-phenylbutadiene (E)-1k [15]. A 4 : 1 mixture of (E)-and (Z)-1-(4-methoxyphenyl)butadiene 1l was obtained in 51% yield by acid-promoted dehydratation of 1-(4-methoxyphenyl)but-3-en-1-ol, a compound resulting from the addition of allylmagnesium chloride to p-anisaldehyde [16].…”

Section: Methodsmentioning

confidence: 99%

“…Prepared according to[15] [36].Colorless oil. UV (MeCN): 278 (24200), 232 (8800), 225 (12300), 219 (12500), 209 (13800), 197 (10300).…”

mentioning

confidence: 99%

Substituent Effect on the Competition between Hetero-Diels-Alder and Cheletropic Additions of Sulfur Dioxide to 1-Substituted Buta-1,3-dienes

Roversi¹,

Monnat²,

Vogel³

et al. 2002

HCA

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The reactivity of sulfur dioxide toward variously substituted butadienes was explored in an effort to define the factors affecting the competition between the hetero-Diels-Alder and cheletropic additions. At low temperature (< À 708), 1-alkyl-substituted 1,3-dienes 1 that can adopt s-cis-conformations add to SO 2 in the hetero-Diels-Alder mode in the presence of CF 3 COOH as promoter. In the case of (E)-1-ethylidene-2-methylidenecyclohexane ((E)-4a), the [4 2] cycloaddition of SO 2 is fast at À 908 without acid catalyst. (E)-1-(Acyloxy)buta-1,3-dienes (E)-1c, (E)-1y, and (E)-1z with AcO, BzO, and naphthalene-2-(carbonyloxy) substituents, respectively also undergo the hetero-Diels-Alder addition with SO 2 CF 3 COOH at low temperatures, giving a 1 : 10 mixture of the corresponding cis-and trans-6-(acyloxy)sultines c-2c,y,z and t2c,y,z, respectively). Above À 508, the sultines undergo complete cycloreversion to the corresponding dienes and SO 2 , which that add in the cheletropic mode at higher temperature to give the corresponding 2-substituted sulfolenes ( 2,5-dihydrothiophene 1,1-dioxides) 3. The hetero-Diels-Alder additions of SO 2 follow the Alder endo rule, giving first the 6-substituted cis-sultines that equilibrate then with the more stable trans-isomers. This statement is based on the assumption that the SO group in the sultine prefers a pseudo-axial rather than a pseudo-equatorial position, as predicted by quantum calculations. The most striking observation is that electronrich dienes such as 1-cyclopropyl-, 1-phenyl-, 1-(4-methoxyphenyl)-, 1-(trimethylsilyl)-, 1-phenoxy-, 1-(4-chlorophenoxy)-, 1-(4-methoxyphenoxy)-, 1-(4-nitrophenoxy)-, 1-(naphthalen-2-yloxy)-, 1-(methylthio)-, 1-(phenylthio)-, 1-[(4-chlorophenyl)thio]-, 1-[(4-methoxyphenyl)thio]-, 1-[(4-nitrophenyl)thio]-, and 1-(phenylseleno)buta-1,3-diene, as well as 1-(methoxymethylidene)-2-methylidenecyclohexane (4f) do not equilibrate with the corresponding sultines between À 100 and À 108, in the presence of a large excess of SO 2 , with or without acidic promoter. The hetero-Diels-Alder additions of SO 2 to 1-substituted (E)-buta-1,3-dienes are highly regioselective, giving exclusively the corresponding 6-substituted sultines. The 1-substituted (Z)-buta-1,3-dienes do not undergo the hetero-Diels-Alder additions with sulfur dioxide.

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Synthesis of acetylenedicarboxylic acid esters and asymmetric Diels–Alder reactions of the bis(methyl (S)-lactyl) ester

Cited by 18 publications

References 24 publications

Synthesis of Dihydrobenzofurans via Palladium-Catalyzed Heteroannulations

Synthesis of Dihydrobenzofurans via Palladium-Catalyzed Heteroannulations

Nonmigratory internal plasticization of poly(vinyl chloride) via pendant triazoles bearing alkyl or polyether esters

Substituent Effect on the Competition between Hetero-Diels-Alder and Cheletropic Additions of Sulfur Dioxide to 1-Substituted Buta-1,3-dienes

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