2-Methoxy-4-methyl-3,4-dihydro-H-pyran

H-Pyran, 2-alkoxy-4-methyl-2,3-dihydro-conformation, 3, 630 4H-Pyran, 2-amino-IR spectra, 3, 593 synthesis, 3, 758 4H-Pyran, 4-benzyIidene-synthesis, 3, 762 4H-Pyran, 2,3-dihydro-halogenation, 3, 723 hydroboration, 3, 723 oxepines from, 3, 725 oxidation, 3, 724 reactions, with acids, 3, 723 with carbenes, 3, 725 4H-Pyran, 5,6-dihydro-synthesis, 2, 91 4H-Pyran, 2,6-diphenyl-hydrogenation, 3, 777 4 H-Pyran, 6-ethyl-3-vinyl-2,3-dihydro-reactions, with acids, 3, 723 4H-Pyran, 2-methoxy-synthesis, 3, 762 4H-Pyran, 2,4,4,6-tetramethyI-IR spectra, 3, 593 4H-Pyran, 2,4,6-triphenyl-IR spectra, 3, 593... 

Dihydro-2-methoxy-4-methyl-2H-PYRAN, 34, 29, 71 3, 4-Dihydro-2 (1 H) -naphth alenonf., 32, 97, 99... 

Catalytic cyclopropanation of alkenes with diazomalonates is sometimes carried out with copper powder, but it appears that copper(I) halide/trialkyl phosphite complexes (for a procedure see Houben-Weyl Vol. E19b, p 1113), bis(acetylacetonato)copper(II), " ° and tet-raacetatodirhodium can be employed more advantageously (Table 13, entries 7-9). For the cyclopropanation of styrene with dicyclohexyl diazomalonate, however, copper(I) triflate was the catalyst of choice, while intramolecular C —H insertion at the cyclohexyl ring took place in the presence of tetraacetatodirhodium. A detailed comparison of copper catalysts for the cyclopropanation of cyclohexene, 1-methyl- and 1,2-dimethylcyclohexene, (Z)- and ( )-hept-2-ene with dimethyl diazomalonate, including competitive reaction pathways such as allylic C-H insertion and carbene dimer formation, is available. The catalyzed interaction between diazomalonic esters and enol ethers leads to cyclopropanes in some cases (e.g. ethoxymethylenecyclohexane to dimethyl 2-ethoxyspiro[2.5]octane-l,l-dicarboxylate ) and to different products in other cases (e.g. 1-methoxycyclohexene, 2-methoxy-3,4-dihydro-2/7-pyran ). This behavior is attributed to the occurence of stabilized dipolar intermediates in these reactions. 

H-Pyran, 3,4-dihydro-2-methoxy-4-methyl-synthesis, 3, 772 2/f-Pyran, dimethoxy-reactions... 

The structure of pironetin was determined to be (5/ ,6/ )-5-ethyl-5,6-dihydro-6[(jE )-(2/ ,35,4/ ,55)-2-hydroxy-4-methoxy-3,5-dimethyl-7-nonenyl]-2H-pyran-2-one by FAB-MS, H and 13C NMR, COSY, COLOC, DEPT, IR, X-ray crystallographic analyses and adapted Mosher s method to determined the absolute configuration [74]. The biosynthesis of pironetin appeared to involve assembly of acetate, propionate and butyrate precursors. Four fermentation experiments were carried out in order to determine the biosynthetic origin of the carbon skeleton and oxygen atoms of pironetin. [1-13C] Acetate, [2-13C]acetate, [1,2-13C] acetate, [l-13C]propionate, [l-1 C]butyrate and L-[methyl-I3C]methionine were led separately to Streptomyces sp. culture and pironetin was isolated and purified. Analysis of pironetin by 13C NMR showed that pironetin was derived from four acetate units, two propionate units, one butyrate unit and one methyl unit of methionine [78] (Fig. 4). 

Updated Entry replacing F-00654 2,3-Dihydro-2,5,8-trihydr oxy-6-methoxy-2-methyl-4li-naphtho[2,3-h]pyran-4-one, 9CI [3748-39-8]... 

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