5-Hydroxy-2,2-dimethyl-6- chromene,

Chroman-2-ylmethanol, (5)-6-hydroxy-2,5,7,8-tetramethyl-synthesis, 3, 779 Chromene, 3-acetyl-2-methoxy-synthesis, 3, 750 Chromene, 2-alkyl-synthesis, 3, 749 Chromene, 4-aryloxymethyl-synthesis, 3, 742-743 Chromene, bis(2,2-dimethyl-mass spectra, 3, 604 Chromene, 2,3-dichloro-synthesis, 3, 753 Chromene, 2,2-dimethyl-IR spectra, 3, 594 mass Spectra, 3, 604 molecular dimensions, 3, 621 synthesis, 3, 743, 749, 751 Chromene, 3-fluoro-2,2-dimethyl-synthesis, 3, 748 Chromene, 5-hydroxy-synthesis, 3, 745... 

H-Chromen 5,7-(bzw. 6,7)-Dimeth-oxy-2,2-dimethyl- VI/4, 226 Cyclobuten 3,4-Dioxo-2-(l -hexinyl)-1-isopropyloxy- E15/2. 1421 (Ether-Spalt.) E17f, 804 [1,2-(OR)2 - 4-OH - 4-inyl -3-oxy-cyclobutan/HCl] Cydohexan trunj-2-Benzoyloxy-l-hydroxy- VI/la,l, 367, 379 Cydopentan... 

S 2,2-dimethyl-5-hydroxy-6-(3-methyl-2- butenyl)-7-[2-(4 - hydroxyphenyl)ethyl]chromene Lethocolea glossophylla 99... 

Precocene II (125) and other chromenes have been synthesized and screened for their effect on the cloth moth. Precocene II has larvicidal properties. A trifluoro-compound (126), related to precocene, has been synthesized from 3,4-dimethoxyphenol, trifluoroacetone, and allylmagnesium bromide. Several natural chromenes, for example 6-acetyl-2,2-dimethyl-5-hydroxy-8-methoxy-2//-chromene, have been synthesized from the appropriate substituted 2-hydroxyacetophenone and either 2-methylbut-3-en-2-ol or 3-chloro-3-methylbut-l-yne. 2//-Chromenes are rarely prepared from chromanones, but a direct conversion of substituted 2,2-dimethylchromanones, e.g. (127), in high yield, into 2H-chromenes, e.g. (128), has been achieved by the action of PCls. °... 

However, when 36 was heated with a-amino heterocycles or with cyclic 1,3-dicarbonyl or potential 1,3-dicarbonyl compounds, 3-heteroarylp)rr-azol derivatives were obtained. In this manner 36 afforded, when heated with 2-aminopyridine and 3-amino-lH-pyrazol in acetic acid under reflux for 2 h and 5 h, respectively, 3-(5-ethoxy-l-phenyl-lH-pyrazol-3-yl)-4H-pyrido[l,2-fl]pyrimid-4-one (38) and 6-(5-ethoxy-l-phenyl-lH-p5rrazol-3-yl)pyrazolo[l,5-fl]pyrimid-7(lH)-one (39) in 70% and 77% 5deld, respectively. Similarly, 36 afforded with cyclicjS-dicarbonyl compounds, such as 4-hydroxy-6-methyl-2H-pyran-2-one and 5,5-dimethylcyclohexane-l,3-dione by heating in acetic acid for 4 h and 8 h, respectively, the corresponding 3-(5-ethoxy-l-phenyl-lH-pyrazol-3-yl)-7-methyl-2H,5H-pyrano[4,3- 7]pyran-2,5-dione (40) and 3-(5-ethoxy-l-phenyl-IH-pyrazol-3-yl)-7,7-dimethyl-7,8-dihydro-2H-chromene-2,5-dione (41) in 26% and 82% yield, respectively (Scheme 15). 

C3oH,o03, Mr 458.73, mp. 100-101 C. A component of the latex m the toadstools Lactarius fuliginosus and L picinus (Basidiomycetes). When the fruit bodies are injured the mild-tasting ester is enzymatically saponified to 4-methoxy-2-(3-methyl-2-butenyl) phenol which is responsible for the bitter taste of the fungi. The phenol is unstable and after some time is oxidized to 6-methoxy-2,2-dimethyl-2//-chromene, 2-(l-hydroxy- 1 -methylethyl)-5-methoxybenzofuran, dimeric compounds, and red pigments. M. is thus probably responsible for the pink discoloration of the milk juices on bruising these toadstools. 

Acetylphloroglucinol monomethyl ether heated 12 hrs. at 170-175° with 3-hydroxy-isovaleraldehyde dimethyl acetal and pyridine -> chromene deriv. Y 68%. F. e., also from aldehydes in place of acetals, s. W. M. Bandaranayake, L. Crombie, and D. A. Whiting, Chem. Commun. 1969, 970 cf. H. P. S. Chawla, P. K. Grover, and N. Anand, Indian. J. Chem. 8, 472 (1970). 

Me ether [163734-38-1]. 7-Hydroxy-5-methoxy-2,2-dimethyl-6-(2-methylbutanoyl)chromene. Rhynchoidn B C17H22O4 M 290.358... 

Hydroxy-4,5-dimethyl-2H-chromen-2-one (3d) Solid, mp 243-245 °C reaction time 50 sec yield 92%... 

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