1.4- Dimethyl-3-cyclohexen methyl ketone

Diels-Adler 2,3-Dimethyl- butadiene Methyl vinyl ketone ((C4F4S03)2N)3La 4-Acetyl-1,2-dimethyl-cyclohexene 86... 

Dimethyl-3-cyclohexene carboxaldehyde Dimethylcyclohexyl methyl ketone 3,4-Dimethylcyclopentane-1,2-dione 4,8-Dimethyl-4,9-decadienal 5,9-Dimethyl-4,8-decadienal... 

Methyl propionate 3-Methyl-5-propyl-2-cyclohexen-1-one Methyl propyl ketone Methyl tiglate Methyl p-toluate Methylundecanal dimethyl acetal Methyl 9-undecenoate Methyl 10-undecenoate Methyl valerate Methyl vanillate Musk ketone Musktibetene Myrcene Myrcenol Myrcenyl acetate Myristaldehyde Myrrh gum Myrtenol Myrtenyl acetate Myrtenyl formate Myrtle (Myrtus communis) extract Myrtle (Myrtus communis) oii P-Naphthyi isobutyl ether P-Naphthyl methyl ether Neral Nerol Neryl acetate Neryl butyrate Neryl formate Neryl isobutyrate Neryi isovaierate Neryi propionate Nona-2,4-dienai trans,trans-2,4-Nonadienal 2,6-Nonadien-1-ol... 

Dihydromyrcenol Dihydromyrcenyl acetate Dimethyl benzenebutanol 2,4-Dimethyl-3-cyclohexene carboxaldehyde Dimethylcyclohexyl methyl ketone 4,8-Dimethyl-4,9-decadienal 5,9-Dimethyl-4,8-decadienal Ethyl acetoxyhexanoate Ethyl o-anisate Geranyl butyrate Geranyl formate Geranyl nitrile Greenyl acetate Hexahydrohexamethyl cyclopentabenzopyran Homolinalool Homolinalyl acetate Hydroxycitronellal Hydroxycitronellal dimethyl acetal Hydroxycitronellal methyl anthranilate Hydroxymethylheptyl methyl ketone Isoamyl phenethyl ether Isoamyl salicylate Isobornyl acetate 2-lsobutylquinoline a-Isomethylionone... 

Dimethyl-4-carbethoxy-2-cyclohexen-l-one and 3,5-di-methyl-2-cyclohexen-l-one have always been prepared from acetaldehyde and acetoacetic ester through the Knoevenagel condensation.2 The keto ester has previously been obtained by selective saponification and decarboxylation methods which have involved heating the crude condensation product with water at 140° 2 3 or with sodium ethoxide in alcohol.3 The ketone has been obtained from the same condensation product by prolonged refluxing in 20% sulfuric acid.2-4 6... 

Cyclohexen 3-(Dimethyl-hydrazo-no)-l-methyl- El4b, 488 (aus Keton)... 

Cyclohexen ( + )-l-Acetoxy-2,6-dimethyl-6-ethoxycarbonyl-E15/1, 76 (Keton + R-COOH) Cyclopentan 2-(3-Ethoxy-allyl)-2-ethoxycarbonyl-l-oxo- E15/1. 295 (Claisen-Umlager.) Cyclopropan 2,3-Diethoxycarbonyl-l-(2-methyl-l-propenyl)- E17a, 237 (subst. Cyclopropen + ROOC en-COOR) E18, 891 (Cyclopropen 4- En) 5,8-Dioxa-spiro 3.4 oct-l-en 2-Butyl-(or tert.-ButyI)-1 -isopropyloxy-3-oxo- E17f, 805 [l,2-(OR)j —4 OSiRj — 4-R — 3-oxo —cyclobuten + l,2-(OSiR3)2 — ethan] Ethan 1,1-Diethoxy-2-(4-methoxy-phenoxy)- E6b/1, 94 f, [OH -> 0-CH2-CH(0R)2]... 

Moreover, the formation of enoxy-silanes via silylation of ketones ) by means of N-methyl-N-TMS-acetamide (7 72) in presence of sodium trimethylsilanolate (7 72) was reported in 1969 and since then, the use of silylating reagents in presence of a catalyst has found wide appreciation and growing utilization as shown in recent pa-pers 2 ) (Scheme 27). Diacetyl (181) can be converted by trifluoromethylsul-fonic acid-TMS-ester (182) into 2,3-bis(trimethylsiloxy)-l,3-butadiene (782) ) (for the application of 782 to nitriles, see )). Propiophenone (184) gives by treatment with ethyl TMS acetate (785)/tetrakis(n-butyl)amine fluoride l-trimethylsiloxy-2-methyl-styrene (786) ), Cyclohexanone reacts with the combination dimethyl-TMS-amine (787)/p-toluenesulfonic acid to 1-trimethylsiloxy-l-cyclohexene (788) ). Similarly, acetylacetone plus phenyl-triethylsilyl-sulfide (789) afford 2-triethylsiloxy-2-pentene-4-one (790) ). 

The retrosynthetic disconnection of isocomene leads primarily to the intermediate tertiary carbenium ion 1, which may arise from the intermediate carbenium ion 2 by anionotropic 1,2-alkyl shift. The latter turns out to be the protonation product of the tricycle 3 containing an exocyclic CC-double bond which is generated by a WiT-TiG-methylenation of the tricyclic ketone 4. The concept behind this is formation of the cyclobutane ring in 4 by means of an intramolecular [2-l-2]-photocycloaddition of the 1,6-diene 5. The enone substructure in 5 results from hydrolysis of the enolether and dehydration of the tertiary alcohol function in (65)-l-alkoxy-2,4-dimethyl-3-(2-methyl-l-penten-5-yl)cyclohexene 6. The tertiary alcohol 6 emerges from a nucleophilic alkylation of (65)-3-alkoxy-2,6-dimethyl-2-cyclohexen-l-one 7 with metallated 5-halo-2-methyl-l-pentene obtained by GrigNARD reaction or... 

The allylalkohol 6 turns out to be the obvious precursor of the protected diol 5, and 6 reasonably arises from a Shapiro coupling of cyclohexadienyllithium 7 with the cyclohexene-4-aldehyde 8 which is the product of oxidation and subsequent diol protection of the bicyclic hydroxylactone 9 the latter emerges from rearrangement of the Diels-Alder cycloadduct 13 of 3-hydroxy-2-pyrone 14 as the diene and 4-hydroxy-2-methyl-2-butenoate 15 as the electron-deficient dienophile. The cyclohexadienyllithium 7 originates from the sulfonylhydrazone of the ketone 10 which is, once again, a Diels-Alder cycloadduct of the protected 3-hydroxymethyl-2,4-dimethyl-l,3-pentadiene 12 and ketene 11 as the dienophile. 

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