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A toxicologic and dermatologic review of 4-(2,4,6-trimethyl-3-cyclohexen-1-yl)-3-buten-2-one when used as a fragrance ingredient is presented.

Two kinds of trifluoromethylated spiro or fused cyclic compounds were synthesized via the unexpected direct alpha,alpha'-dialkylation of (E)-4-ethoxy-1,1,1-trifluoro-3-buten-2-one (1) with silyl enol ethers in the presence of boron trifluoride etherate.

The synthesis of 1,1,1-trichloro-4,4-diethoxy-3-buten-2-one and three trichloroacetylacetate derivatives from the acylation reaction of respective trialkyl orthoacetates and orthopropionates with trichloroacetyl chloride in good yields, is reported. The title compounds were used for the regiospecific preparation of two isoxazoles and five pyrazoles in the cyclocondensation with hydroxylamine and hydrazines, respectively. The transformation of the trichloromethyl group under mild conditions into carboxylic groups is also described.

A new method for beta-phenol annulation involving base-induced [4C + 2C] cycloaromatization of readily available 4-bis(methylthio)-3-buten-2-one with a variety of cyclic and acyclic active methylene ketones has been reported. Appropriate choice of ketones allows synthesis of diverse frameworks such as dihydroindan, tetrahydronaphthalenes, their higher homologues, dihydro/octahydrophenanthrenes, anthracene, and heteroannulated analogue in high yields with regiocontrol of phenolic functionality.

A toxicologic and dermatologic review of 4-(1,2-epoxy-2,6,6-trimethylcyclohexyl)-3-buten-2-one when used as a fragrance ingredient is presented.

The Friedel-Crafts condensation of acetyl chloride and vinylidene chloride (1,1-dichloroethylene) in dichloromethane solution gives 4,4,4-trichloro-2-butanone (2), which is smoothly dehydrohalogenated with triethylamine to produce 4,4-dichloro-3-buten-2-one (1) in excellent yield

1-Bromo-3-buten-2-one is investigated as a building block for organic synthesis. Reduction to the corresponding alcohol works best with lithium aluminium hydride, reaction with primary amines gives 5-membered-aza-heterocycles in moderate yields and reaction with activated methylene compounds to form 5-membered-carbocycles gave unsatisfactory yields when a one-pot-procedure was used. The first step of a stepwise protocol, a Michael addition, is discussed.

Synthetic procedures for the preparation of 1-bromo-3-butyn-2-one and 1,3-dibromo-3-buten-2-one are given. These compounds are prepared from 2-bromomethyl-2-vinyl-1,3-dioxolane, which can readily be prepared from 2-ethyl- 2-methyl-1,3-dioxolane. The synthetic routes are as follows: 2-bromomethyl-2-vinyl-1,3-dioxolane is converted to 2-(1,2-dibromoethyl)-2-bromomethyl-1,3-dioxolane. Double dehydrobromination with tBuOK affords 2-ethynyl-2-bromomethyl-1,3-dioxolane. Formolysis with formic acid gives 1-bromo-3-butyn-2-one. Deacetalized 2-bromoethyl-2-vinyl-1,3-dioxolane was treated with Br2 and Li2CO3/12-crown-4 in tetrahydrofuran to give 1,3-dibrom-3-buten-2-one in moderate yield.

A toxicologic and dermatologic review of 4-(3,5,6-trimethyl-3-cyclohexen-1-yl)-3-buten-2-one when used as a fragrance ingredient is presented.

A toxicologic and dermatologic review of 3-methyl-4-(2,4,6-trimethyl-3-cyclohexen-1-yl)-3-buten-2-one when used as a fragrance ingredient is presented.

Novel heterocyclizations have been investigated based on the reaction of the complex between trifluoromethanesulfonic anhydride and 4-dimethylamino-1,1,1-trifluoro-3-buten-2-one with 2,2'-biindolyl and N,N'-dipyrrolylmethane leading to closure of 6- or 7-membered rings.

C 10 H 8 BrNO 3 , M r =270.08, orthorhombic, Pna2 1 , a=11.137 (1), b=17.361 (2), c=5.5641 (4) A, V=1075.8 (2) A 3 , Z=4, D x = 1.666 g cm -3 , F(000)=536, λ(Mo kα)=0.71073 A, μ=37.67 cm -1 , T=298 K, R=0.034 for 690 unique reflections with I≥3σ(I). The nitro group is coplanar with the C=C bond but the additional π bonding of the C=O group and the phenyl ring means that they are twisted relative to the C=C bond plane by about 90 and 79 o , respectively

3-Buten-2-one cyanohydrin diethyl phosphate reacted regio-and stereo-selectively with a variety of dialkyl cuprates and ethoxycarbonylmethylcopper giving γ-coupling products, 2-alkenenitriles, one of which was used to synthesize (±) - (E) -Nuciferol.

The crystal and molecular structure of a hydroxy derivative of α-ionone, 4-(hydroxy-2,6,6-trimethyl-2-cyclohexenyl)-3-buten-2-one, was studied by means of X-ray analysis. The atoms including the conjugated double bond in the side chain and those around the double bond in the ring form planes orthogonal to each other.

The reported Robinson annelation of 2-methylcyclohexanone with 3-penten-2-one has been reexamined. In contrast to the previous result, it was found that the reaction product was not only obtained in a low yield, but also the solvent-depending stereoselectivity in the formation of cis-4,4a-dimethyl-4,4a,5,6,7,8-hexahydronaphthalen-2(3H)-one (3a) and its trans isomer (3b) was considerably lower than that reported. As expected, regioisomers, 4β,8α-dimethyl-4,4aβ,5,6,7,8-hexahydronaphthalen-2(3H)-one and 4β,8β-dimethyl-4,4aα,5,6,7,8-hexahydronaphthalen-2(3H)-one, were also formed in the annelation. A similar tendency was observed in the reaction with 4-phenyl-3-penten-2-one. The annelation products, 3a, 3b, cis-4-phenyl-4a-methyl-4,4a,5,6,7,8-hexahydronaphthalen-2(3H)-one, and trans-4-phenyl-4a-methyl-4,4a,5,6,7,8-hexahydronaphthalen-2 (3H)-one, were also synthesized by an alternative route.

B-1-Hexinyl-9-borabicyclononan (I) reagiert mit Benzalacetophenon (II) quantitativ zum Addukt (III).

Reaction of lithiated 3-cyano-1(3H)-isobenzofuranone (7) with 5-substituted 2-furfuralacetones 6a-c and subsequent O-methylation of the resulting naphthohydroquinones afforded 2-acetyl-3-furylnaphthalenes 8a-c in good yields. Annulation of the dialkoxyphthalides 12a, b with 6a could also be carried out to give 13a, b. The 5-tert-butoxy-2-furyl compounds were stereoselectively transformed into (1R*, 3R*, 4R*)-pyrano-γ-lactones 16a, 18a, b in high yields by a modification of the Kraus method (LiAlH4 reduction followed by treatment of the product carbinol with p-toluenesulfonic acid (TsOH) in acetonitrile and then with 1, 8-diazabicyclo[5.4.0]undec-7-ene in toluene at low temperatures). The 5-methoxy-2-furyl compound 9b also afforded 16a stereoselectively in one step (treatment with TsOH), but this compound was less effective as a substrate of the pyrano-γ-lactone annulation since a side reaction leading to the spiro-γ-lactone 17 became significant. The 5-phenylthio compound 9c failed to give 16a under a variety of conditions.

3-Buten-2-one cyanohydrin diethyl phosphate reacted regio-and stereo-selectively with a variety of dialkyl cuprates and ethoxycarbonylmethylcopper giving γ-coupling products, 2-alkenenitriles, one of which was used to synthesize (±) - (E) -Nuciferol.