24871-12-3Relevant articles and documents
Intramolecular Reductive Cyclization of Unsaturated Keto- or Aldo-esters by Samarium(II) Di-iodide: A Ready Synthesis of Bicyclic g-Lactones
Fukuzawa, Shin-ichi,Iida, Masahiro,Nakanishi, Akira,Fujinami, Tatsuo,Sakai, Shizuyoshi
, p. 920 - 921 (1987)
Treatment of unsaturated keto- or aldo-esters with SmI2 in tetrahydrofuran (THF) or THF-hexamethylphoshoramide affords bicyclic γ-lactones in moderate to good yields.
RECYCLABLE POLYMERS BASED ON RING-FUSED GAMMA-BUTYROLACTONES
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, (2020/02/23)
The invention discloses a class of new polymers, trans-ring-fused poly(4-hydroxybutyrate)s (RF-P4HB) that exhibit a unique set of properties, including robust thermal stability and mechanical strength, quantitative recyclability to the building block monomers via thermolysis and/or chemical catalysis, and convenient production from the chemical ring-opening polymerization under ambient temperature and pressure. Another unique property is the formation of crystalline stereocomplexed polymers with high melting temperature upon mixing the two enantiomeric RF-P4HB chains via stereocomplexing co-crystallization. This invention also provides the corresponding ring-fused lactone monomer structures that enable the synthesis of the RF-P4HB polymers, through trans-fusing of rings to the parent γ-butyrolactone ring. Furthermore, a polymerization or copolymerization process for the synthesis of RF-P4HB polymers and copolymers is disclosed.
(HMe 2 SiCH 2) 2: A Useful Reagent for B(C 6 F 5) 3 -Catalyzed Reduction-Lactonization of Keto Acids: Concise Syntheses of (-)- cis -Whisky and (-)- cis -Cognac Lactones
Xie, Hengmu,Lu, Ji,Gui, Yingying,Gao, Lu,Song, Zhenlei
supporting information, p. 2453 - 2459 (2017/10/06)
(HMe 2 SiCH 2) 2 has been utilized as a useful reagent for B(C 6 F 5) 3 -catalyzed reduction-lactonization of keto acids to synthesize γ- and δ-lactones. The process led concisely to (-)- cis -whisky and (-)- cis -cognac lactones in respective overall yields of 32% and 36%.
Efficient Oxidative Cleavage of Tetrahydrofuran-2-methanols to γ-Lactones by a 2-Iodobenzamide Catalyst in Combination with Oxone
Yakura, Takayuki,Horiuchi, Yuto,Nishimura, Yushi,Yamada, Akihiro,Nambu, Hisanori,Fujiwara, Tomoya
supporting information, p. 869 - 873 (2016/04/05)
An environmentally friendly oxidative cleavage of tetrahydrofuran-2-methanols to the corresponding γ-lactones using a catalytic amount of 2-iodo-N-isopropylbenzamide has been developed. The reaction of various tetrahydrofuran-2-methanols with the catalyst in the presence of Oxone (2 KHSO5·KHSO4·K2SO4) as a co-oxidant in DMF at room temperature successfully affords the corresponding lactones in good to high yields, and recovery of the catalyst is readily accomplished using a reductive work-up. This method is notable because it enables the transformation of tetrahydrofuran-2-methanols to γ-lactones under mild conditions without the use of any toxic heavy metals.
On the stereochemical course of the addition of allylsilanes to aldehydes
Denmark, Scott E.,Weber, Eric J.,Almstead, Neil G.,Wolf, Larry M.
experimental part, p. 7701 - 7718 (2012/09/11)
Model compounds 3 and 5 have been studied to determine the orientation of the reacting double bonds in the transition state of the allylmetal-aldehyde addition. These models were designed to remove any intrinsic steric bias for the formation of the bicyclic products that would obfuscate a stereoelectronic contribution to the transition states. Model system 3 revealed a modest preference for the synclinal transition state, albeit in very low yields. Model system 5 underwent selective and largely Lewis acid independent cyclization primarily via a synclinal transition state. The high proximal selectivity observed in these cyclizations likely reflects the selectivity of an unhindered allylmetal-aldehyde addition for the synclinal transition state and results from a stereoelectronic preference, not an intrinsic steric bias, for the synclinal arrangement of double bonds.
Rhodium(II)-catalyzed enantioselective intramolecular CH insertion with alkyl diazo(trialkylsilyl) acetates
Mueller, Paul,Lacrampe, Fabienne,Bernardinelli, Gerald
, p. 1503 - 1510 (2007/10/03)
The decomposition of cyclohexyl diazo(triethylsilyl)acetate 2a and the t-butyl derivatives 3a,b with [Rh2{(S)-nttl}4] and similar chiral Rh(II)-catalysts proceeds in toluene at room temperature to produce silylated lactones in up to 90% yield. The reaction is highly stereoselective. Enantioselectivities of up to 79% have been observed.
Nucleophilic Additions to Fused Bicyclic Five-Membered Ring Oxocarbenium Ions: Evidence for Preferential Attack on the Inside Face
Smith, Deborah M.,Tran, Michelle B.,Woerpel
, p. 14149 - 14152 (2007/10/03)
Evidence is provided that nucleophilic attack on five-membered ring oxocarbenium ions occurs from the inside face of the envelope. An eight-five fused-bicyclic system in which two substituents are constrained to pseudoequatorial positions underwent nucleophilic addition with selectivity that was comparable to an unconstrained monocyclic system. On the other hand, a bicyclic six-five analogue underwent reaction with low selectivity. This observation indicates that minimization of eclipsing interactions by attacking inside the envelope is not enough to control selectivity, but that the changes in the overall three-dimensional structure of the ring must be favorable as well. In the bicyclic six-five series, the six-membered ring is accommodated in the cation, but it destabilizes the transition state structure leading to the first-formed product of inside attack.
Synthesis of γ-lactones and unsaturated bis γ-lactones via Cu-Fe-mediated reductive cyclization of di- and tri-α-halogenated carboxylic esters
Somech, Iris,Shvo, Youval
, p. 153 - 159 (2007/10/03)
A new synthetic route to γ-substituted γ-butyrolactones from alkenes and α-dichloro ester, in the presence of CuCl (catalytic) and Fe(0) (stoichiometric) in acetonitrile, was established. A study of this reaction has demonstrated that the overall process consists of the following reaction steps: (a) addition of the dichloro ester to the olefin via CuCl catalysis; (b) selective reduction of the α-chloro atom in the resulting adduct by Fe(0); (c) cyclization of the resulting γ-chloro ester to γ-butyrolactone. Yields were improved by first carrying out step (a), then steps (b) and (c) in one pot. Selectivity was improved in the presence of a small amount of water. α-Trichloro esters also generated the γ-substituted γ-butyrolactone, albeit in lower yields and selectivity. The latter reaction gave rise to the formation of interesting by-products, namely new unsaturated bis-lactones.
Formation of organomagnesium compounds via EtMgBr-mediated radical cyclization of allyl β-iodoacetals
Inoue, Atsushi,Shinokubo, Hiroshi,Oshima, Koichiro
, p. 651 - 653 (2007/10/03)
(Graph presented) Treatment of allyl β-iodoacetals with ethylmagnesium bromide in THF provided tetrahydrofuran derivatives in good yields. On the other hand, the reaction in DME provided tetrahydrofuranylmethylmagnesium compounds in good yields.
Transition-metal-catalyzed carbenoid reactions of sulfonium ylides
Mueller, Paul,Fernandez, Daniel,Nury, Patrice,Rossier, Jean-Claude
, p. 935 - 945 (2007/10/03)
Olefins undergo cyclopropanation with diphenylsulfonium (ethoxycarbonyl)methylide (=diphenyl-sulfonium 2-ethoxy-2-oxoethylide; 3a) in the presence of chiral Cu(I) or Rh(II) catalysis, trans/cis Ratios and ee's of the cyclopropanes 6 obtained with this ylide in the presence of a chiral Cu(I) catalyst 7 are identical with those obtained with ethyl diazoacetate (4). In the case of catalysis with Rh(II), the trans/cis ratios of the cyclopropanes as well as the enantioselectivity change slightly upon going from the ylide 3a to diazoacetate 4.
