4- Methyl-4-phenyl-2-cyclohexenone

The photorearrangement of 4-methyl-4-phenyl-2-cyclohexenone was shown by Dauben and co-workers to be very solvent dependent/761 In aprotic, nonpolar solvents only two products were reported ... 

The butyllithium-generated anion of an allylic sulfone was reported to add to conjugate enones, but different regioselectivity was observed for 2-cyclohexenone (1,4-y) and 3-penten-2-one (1,4-a), as shown in equation (31). Clean 1,4-a additions to both acyclic and cyclic enones can be realized when the lithio carbanions are allowed to react in the presence of HMPA (2 mol equiv.) at -78 C. Under these conditions, allyl phenyl sulfone reacts with 2-cyclohexenone. 2-methyl-2-cyclopentenone and 3-methyl-2-cyclohexenone, giving the corresponding 1,4-a adducts as a 75 25 mixture of two dia-stereoisomers. In the reaction of allylic phenyl sulfone with an acyclic enone, 4-methyl-3-penten-2-one,... 

Photoaddition of cyclohexenones with moderate electron-donating groups such as methyl, phenyl, and acetoxy at the enone 3-position proceeds smoothly with the expected HH regioselectivity except for a few cases [24,51a]. 3-Methyl- (10) and 3-acetoxycyclohexenone (11) react with isobutene (12) or 1,1-diphenylethylene (13) to provide the opposite regioisomeric products as shown... 

Miyaura proposed the prototype of the catalytic cycle (M = Pd, Scheme 2.11) in 2004. For the conjugate addition to 3-methyl-2-cyclohexenone outlined in Scheme 2.10, the first step involves transmetalation of cationic Pd(II)-phenylborate complex A to generate a phenyl-palladium complex B. Complex B undergoes ligand exchange to form a more stable... 

The chiral borohydride formed from l,2 5,6-di-0-cyclohexylidene-a-D-glucofuranoside, 9-BBN, and potassium hydride gives good chiral induction in reactions with ketones reduction of acetophenone led to (/f)-methyl phenyl carbinol in 77% e.e.92 Aminoalcohols derived from D-glucose can catalyse enantioselective Michael additions of arylthiols to cyclohexenone. 3... 

A detailed study of the cycloaddition of trifluoromethylethene has appeared as has work on a-siloxy-a -unsaturated ketones as dienophiles under Lewis-acid catalysis. Amongst the new dienophiles that have been reported are the two novel ketene equivalents methyl methoxypropiolate (129) and methyl phenyl-thiopropiolate (130). A series of 3-(acyloxy)but-3-en-2-ones (131) has been prepared and used as dienophiles in a route to anthracylinones, and, as part of a route to highly functionalized cyclohexenones, the vinyl sulphone (132) has been used in a Diels-Alder reaction with various dienes. ... 

To a suspension of cuprous iodide (0.03 mol) in 100 ml THF was added 25 ml dimethyl sulfide. The solution was cooled to -78 °C, phenyl magnesium bromide (0.06 mol) dissolved in diethyl ether added, stirred one hour, and 2-cyclohexenone (0.03 mol) dissolved in 10 ml THF added. The mixture was warmed to 0°C over 2 hours then re-cooled to -78 °C. It was treated with 15 ml hexamethyl-phosphoramide, stirred 30 minutes, treated with methyl cyanoformate (0.09 mol), and warmed to ambient temperature overnight. The mixture was poured into 100 ml 2M HCl, the organic phase separated, and the aqueous phase extracted with CH2CI2. The combined organic extracts were concentrated, the residue triturated with NH4CI, water, brine, dried, and 3.2 g product isolated as an oil. 

The stabilizing effect of the secondary orbital interactions of the trifluoromethyl substituent with dienes is exemplified in the cycloaddition reaction of a-(trifluorornethyl)styrene (7) with Danishefsky s diene 4. A phenyl substituent is known to stabilize the endo-phenyl transition state. Furthermore, the steric hindrance of a trifluoromethyl group should favor its exo approach. However, cycloadducts 8 are obtained in a 1 1 mixture of transicis stereoisomers which are converted into the cyclohexenone 9. Under the same thermal conditions, a-methyl-styrene is unreactive.5... 

Cyanoselenation of aldehydes with phenyl selenocyanate in the presence of BusP gave a-(arylsele-no)nitriles. Selenylation of nitriles aSiST treatment with 2 equiv. of base also led to the formation of a-selenonitriles. Their lithiated derivatives undergo smooth alkylation with methyl iodide (80%) and Michael addition to cyclohexenone in 90% yield (Scheme 30). ... 

Reaction of an a-(phenylthio)nitrile with base, such as LDA, followed by an aldehyde or a ketone gives a 1,2-addition product in good yield, while the use of a, -unsaturated aldehy s and ketones usually leads to the 1,4-addition product. Conjugate addition of the a-(phenylthio)acetonitrile anions to 2-methyl- or 2-phenyl-2-cyclohexenones or 2-methyl-2-cyclopentenones, followed by acid quenching under kinetic control, leads to different ratios of cis and rr[Pg.561]

Representative procedure synthesis of 5-methyl-5-phenyl-2,3-dipropyl-2-cyclohexenon ... 

Changing the substituent on the p-position of the cyclohexenone from methyl to ethyl, butenyl or phenyl leads to significant drops in conversion and enantioselectivity. 

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