Methyl Homologues of Methyl Jasmonate and Methyl Dihydrojasmonate (Hedione®) from Sorbyl Alcohol

Treatment of cycloalkanone dimethyl acetals 3 – 6 with sorbyl alcohol (=(2E,4E)‐hexa‐2,4‐dien‐1‐ol; 1 ) in the presence of acids afforded the novel cycloalkenones 8, 9, 11 , and 13 via a domino reaction (Claisen rearrangement with intramolecular ene reaction and retro‐ene reaction). Cyclopentenone 8 was readily transformed into 14 and 15 , methyl homologues of racemic methyl jasmonate ( 16 ) and methyl dihydrojasmonate (=Hedione®; 17 ), respectively. The organoleptic properties of 14 and 15 are also discussed.     

Facile Preparation of the Methyl Acetal of Methyl Phenylglyoxylate

The methyl acetal of methyl phenylglyoxylate has been prepared from halophenylethynes, N-iodosuccinimide and catalytic amounts of (hydroxy(p-tosyloxy)iodo)benzene or p-toluenesulfcnic acid in methanol at room temperature.     

Methyl Trifluoropyruvate Diethoxyphosphorylimine

The first example of trifluoropyruvate phosphorylimines was prepared, and its capability for O- and S-amidoalkylation of water, alcohols, and compounds with the SH function was shown. Phenol and 4-methoxyphenol are O-alkylated, while 3-dimethylaminophenol and indole undergo regiospecific C-alkylation at the site of the highest -electron density.     

Convenient Preparation and Spectroscopic Characterization of Methyl Hydrodisulfide and Methyl Deuterodisulfide

Methyl hydrodisulfide and methyl deuterodisulfide have been prepared in a four-step synthesis. These compounds have been characterized spectroscopically including microwave spectra.     

Synthesis of Methyl (Methyl D-and L-Idopyranosid)Uronates from myo-Inositol

Abstract

Methyl (methyl α-D-(9a), α-(9b), β-D-(10a), and β-L-(10b) idopyranosid)uronates were synthesized from myo-inositol. Baeyer-Villiger oxidation of the optically resolved inosose derivatives (3a and 3b) proceeded regioselectively to afford 4a and 4b in high yields, respectively. Ring-opening of the 7-membered hemiacetal-lactones (4a and 4b) with acid and subsequent deprotection gave the title compounds.     

胆酸甲酯(甲基)丙烯酰基衍生物的合成

以(甲基)丙烯酰氯为酰化剂,三乙胺做缚酸剂合成了分子中含有1~3个(甲基)丙烯酰基的胆酸衍生物。结果显示,以酰氯作酰化试剂,胆酸甲酯分子中3个羟基的反应活性顺序是:C3-OH>C12-OH>C7-OH。     

Copolymerization and Copolymers of 2,4,5-Tribromostyrene with Methyl Acrylate and Methyl Methacrylate

Abstract

2,4,5-Tribromostyrene (TBSt) was copolymerized with methyl acrylate (MA) or methyl methacrylate (MMA) in a toluene solution using 2,2′-azobisisobutyronitrile as free radical initiator. The copolymerization reactivity ratios were found to be for the system TBSt / MA r₁= 7.4 ± 1.2 (TBSt) and r₂= 0.1 ± 1.4 (MA) and for the system TBSt / MMA r₁ = 1.8 ± 0.2 (TBSt) and r₂ = 0.1 ± 0.2 (MMA). The e and Q values were also calculated. The initial rate of copolymerization, as well as molecular weight of the obtained copolymers for both system linearly increase as the content of TBSt in the monomer mixture increases. Similar behavior has also been established for the course of the copolymerization reactions to high conversions. The resulting copolymers rapidly decompose at temperatures 20–800°C above the decomposition of corresponding (metha)crylate hompolymers. However, the glass transition temperature increases markedly with increasing TBS content.     

N-(Benzyloxycarbonyl)-L-vinylglycike Methyl Ester from L-Methionine Methyl Ester Hydrochloride

A reproducible, large scale and practical synthesis of N-(benzyloxycarbonyl)-L-vinylglycine methyl ester starting from L-methionine methyl ester hydrochloride is described.     

Methyl propionate radical cation

Examination of the reactions of the long-lived (>0.5-s) radical cations of CD₃CH₂COOCH₃ and CH₃CH₂COOCD₃ indicates that the long-lived, nondecomposing methyl propionate radical cation CH₃CH₂C(O)OCH ₃ ^+· isomerizes to its enol form CH₃CH=C(OH)OCH ₃ ^+· (ΔH _{isomerization} ? ?32 kcal/mol) via two different pathways in the gas phase in a Fourier-transform ion cyclotron resonance mass spectrometer. A 1,4-shift of a β-hydrogen of the acid moiety to the carbonyl oxygen yields the distonic ion ^·CH₂CH₂C⁺ (OH)OCH₃ that then rearranges to CH₃CH=C(OH)OCH ₃ ^+· probably by consecutive 1,5- and 1,4-hydrogen shifts. This process is in competition with a 1,4-hydrogen transfer from the alcohol moiety to form another distonic ion, CH₃CH₂C⁺(OH)OCH ₂ ^· , that can undergo a 1,4-hydrogen shift to form CH₃CH=C(OH)OCH ₃ ^+· . Ab initio molecular orbital calculations carried out at the UMP2/6-31G** + ZPVE level of theory show that the two distonic ions lie more than 16 kcal/mol lower in energy than CH₃CH₂C(O)OCH ₃ ^+· . Hence, the first step of both rearrangement processes has a great driving force. The 1,4-hydrogen shift that involves the acid moiety is 3 kcal/mol more exothermic (ΔH _{isomerization}=?16 kcal/mol) and is associated with a 4-kcal/mol lower barrier (10 kcal/mol) than the shift that involves the alcohol moiety. Indeed, experimental findings suggest that the hydrogen shift from the acid moiety is likely to be the favored channel.     

二氢茉莉酮酸甲酯的合成

庚醛与顺丁烯二酸二乙酯进行游离基加成反应得到庚酰丁二酸二乙酯(3),3脱羧得到γ-酮酸乙酯(4),4在碱性条件下环化为2-戊基-1,3-环戊二酮(5),5与重氮甲烷反应得到2-戊基-3-甲氧基环戊-2-烯酮(6),6与丙二酸二甲酯反应得到(7),7水解、脱羧和酯化得到[2-戊基-3-酮-1-环戊烯]基乙酸甲酯(8),8氢化得到二氢茉莉酮酸甲酯。     

α-环戊基扁桃酸甲酯的合成

苯乙酮酸与环戊二烯基溴化镁发生格氏反应,再经Pd/C催化氢化、甲酯化反应合成了α-环戊基扁桃酸甲酯,总收率23.4%,其结果经1H NMR表征.     

Behavior of Methyl and Propyl Methyl Cellulose Solutions in Longitudinal and Convergent Flows

A mixed ether, propyl methyl cellulose with varied number of propyl groups, was synthesized from commercial water-soluble methyl cellulose. The effect of the number of side propyl groups on the dynamics of aqueous methyl and propyl methyl cellulose solutions in longitudinal and convergent flows was studied. The conditions under which solutions transform into the induced anisotropic state were determined.