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New method for P2P

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Megatherium:
Even though the yields will be low, it is nice to see that the peroxysulfuric acid oxidation works on unsaturated ketones.  Persulfate seems to be a rather usefull compound.  Osmium demonstrated that in Patent US4146582 it can also be used to convert toluene to benzaldehyde  {unable to localize post due to technical reasons }

This P2P synthesis would be super easy, and rather not suspicious.

armageddon:

Rhodium:
Oxydation des aldéhydes ?,?-non-saturés par l'acide peroxoacétique
C. R. Zanesco
Helv. Chim. Acta 49, 1002-1012 (1966) (https://www.thevespiary.org/rhodium/Rhodium/pdf/methyl-cinnamaldehyde.peracid.pdf)

Baeyer-Villiger oxidation of ?-methyl-cinnamaldehyde with peracetic acid. Discussion of the reaction mechanisms at work, and the product distibution under different reaction conditions. Their best yield of P2P enol formate is 52%, and this is easily hydrolyzed to P2P by mere water.
____ ___ __ _

Synthesis of Heterocyclic Compounds from ?-Unsaturated 1,3-Diketo-esters.
Part II. ?-Substituted Styrylpyrazole- and Styrylisoxazole-carboxylic Esters
L. Rateb & G. Soliman
J. Chem. Soc. 1426-1430 (1966) (https://www.thevespiary.org/rhodium/Rhodium/pdf/methylstyrylketones.pdf)

Preparation of various ring-substituted ?-methyl-benzalacetones from benzaldehydes and excess 2-butanone (MEK) with dry HCl gas at -5°C. With references to previous preparations.

moo:
The following article describes oxidation of benzylideneacetone to phenylacetaldehyde enol acetate with peracatic acid in acetic acid buffered with potassium acetate in 60% yield, also other unsaturated ketones relatively close to phenylacetone enol acetate are oxidised and "isolated in yields of 65-80%", 2-benzylidenecyclopentanone among them. What do you think, could the need for 90% hydrogen peroxide be avoided by use of UHP (urea hydrogen peroxide complex) here?


Reaction of peroxyacetic acid with a-aralkylidenecyclanones.
Walton, Henry M.
Journal of Organic Chemistry, 22, 1161-5 (1957).  Journal language unavailable.
CAN 52:29915  ISSN 0022-3263
                                                                                                     
Abstract
The reaction of peroxyacetic acid (I) with a-aralkylidenecyclopentanones and a-aralkylidenecyclohexanones in AcOH media of different acidity resulted in the intrusion of an O atom between the CO and the methylidene C atoms, with the formation of new 5-enoic-5-hydroxy acid d-lactones and 6-enoic-6-hydroxy
acid e-lactones.  In the presence of massive amts. of KOAc further oxidation of the enol lactones under conditions of their formation was effectively suppressed.  a-Furfurylidenecyclohexanone (II) reacted similarly.  p-Anisaldehyde (28.5 g.), 18.0 g. cyclopentanone (III), 200 ml. Et2O, and 200 ml. N NaOH
stirred 64 hrs. at room temp., the aq. layer sepd. and extd. with Et2O, the combined Et2O exts. washed, dried, and concd., and the residue distd. in vacuo gave 30 g. p-anisalcyclopentanone (IV), b25 175 Deg, m. 68-9 Deg (iso-PrOH).  A higher yield of IV was obtained when the same reactants in Et2O and N NaOH were shaken 15 hrs. at room temp.  Furfural (32 g.), 28 g. III, 150 ml. Et2O, and 0.1N NaOH stirred 45 min. and the product distd. in vacuo gave 55 g. furfurylidenecyclopentanone, b15 154 Deg, m. 59-60 Deg (isopropyl ether).  BzH (212 g.), 218 g. cyclohexanone (V), and 1 l. N NaOH refluxed 3 hrs. gave 273 g. benzalcyclohexanone (Va), b10 173-83 Deg, m. 54 Deg (ligroine).  When substituted benzaldehydes were condensed with V, heating under reflux was applied 5-6 hrs.  With less reactive aldehydes (o- and p-chlorobenzaldehyde), two fold molar quantities of V gave improved yields.  The o-Cl deriv. b0.15
128 Deg and the p-Cl deriv. m. 82 Deg.  Furfural (196 g.) added in 2 portions to 200 g. cyclohexanone
and 2 l. N NaOH, after addn. of the first part the temp. reached 34 Deg in 2 hrs.; when the temp. dropped to 30 Deg the remaining half of the ketone was added and stirring continued 21 hrs., and the product isolated as above gave 217 g. II, b0.2 103 Deg, m. 46-7 Deg.  The I reagent was added rapidly with
stirring to a slight excess of cyclanone dissolved or suspd. in a five- or six-fold amt. of the appropriate solvent system.  The reaction was strongly exothermic and the temp. maintained at 30 Deg by cooling; after 20-30 min. the reaction slowed down, quenched by the addn. of Et2O and H2O, when 1.0 atom of active O had been consumed, and the product was isolated from the Et2O soln.  When the Et2O solns. obtained from reaction mixts. contg. massive amts. of KOAc were evapd. the residue usually crystd., furnishing crude lactones RC6H4CH:C.(CH2)n.CH2.C(O).O (VI); in a few cases partial purification by distn. in vacuo was necessary to bring about crystn.  Characterization of VI involved sapon. of the lactones in a slight excess of aq.-alc. alkali and treatment of the sapon. mixt. with semicarbazide reagent.
I (12 ml., contg. 0.076 mole peracid) was added during 10 min. to 14.05 g. Va in AcOH satd. with KOAc; after 40 min., about 93% of the I and 53% of the H2O2 content of the reagent had been consumed and after 70 min. about 95% and 68%, resp.  Extn. with Et2O and sepn. gave 8.4 g. VI (R = H, n = 2) (VIa).
Somewhat less pure material was isolated from the mother liquors to give a total yield of 67% based on I, 62% based on Va.  The following VI were thus prepd. (R, n, m.p. or b.p./mm., solvent of recrystn., m.p. of semicarbazone, recrystn. solvent, and neutralization equiv. are given): H (VIa), 2, 79-80 Deg, isopropyl ether, 162-3.5 Deg, aq. alc., 264; o-Cl, 2, 113.5-14.5 Deg, iso-PrOH, -, -, -; p-Cl, 2, 111-12 Deg, iso-PrOH, -, -, -; p-MeO (VIb), 2, 72-3 Deg, iso-PrOH, 157 Deg, aq. alc., -; 3,4-OCH2O, 2, 96-7 Deg, isopropyl ether-iso-PrOH, -, -, -; H, 3, 70-1 Deg, isopropyl ether, 158-9 Deg, aq. alc., 271; p-Cl, 3, 103-4 Deg, iso-PrOH, 163-3.5 Deg, aq. dioxane, -; p-MeO, 3, 67 Deg, isopropyl ether, -, -, -; H, (from 3-methyl-6-benzalcyclohexanone), 63.5 Deg, isopropyl ether, -, -, -; o-Cl, 3, 88-9 Deg, iso-PrOH, 188-9 Deg (decompn.), aq. dioxane, -; 2-furyl, 3, 137 Deg/1.5, -, 150 Deg, aq. MeOH, 269.  The
corresponding epoxides (VIIa) and (VIIb) were obtained similarly to VIa and VIb; VIIa m. 80 Deg (isopropyl ether) and VIIb m. 64 Deg (iso-PrOH).  They were isolated from mixts. obtained by using AcOH contg. small amts. of alkali acetate as the solvent.  7-Phenyl-6-hydroxy-6-heptenoic acid e-lactone (2.02
g.) was oxidized 16 hrs. at room temp. with 2% KMnO4, 5 g. K2CO3 added, the stirring continued 2 hrs., several small amts. of (CO2H)2 added to discharge the purple color of the soln., the mixt. filtered,
the filtrate concd., and the residue dissolved in H2O, acidified to pH 5, BzOH removed, and the filtrate worked up to give adipic acid.  VIa (1.3 g.) in 12 ml. AcOH treated 1 hr. with I gave 0.73 g. VIIa.  VIIa (0.10 g.) saponified at room temp. in 0.2N KOH in 3 ml. 50% alc. gave the acid, m. 62 Deg (CCl4-ligroine), neutralization equiv. 221.





The first of the two following articles describe a method for Baeyer-Villiger oxidation of unsaturated ketones with both hydrogen peroxide and a solution of sodium hydroxide added simultaneously to the unsaturated ketone in ethanol at -10°C. The formed enol acetate is hydrolyzed in situ, the products for 2-cyclopentylidenecyclopentanone being both 5-cyclopentyl-5-oxovaleric acid (25% yield) and it's ethyl ester (60% yield). Alkaline NaOH is a standard method for epoxidation of unsaturated ketones, so the fact that the reaction has been got to turn out as a Baeyer-Villiger oxidation is quite interesting. Guillanton even shows that the reaction really is a Baeyer-Villiger oxidation and does not proceed through the epoxide. The second article describes use of this reaction for preparing ketocarboxylic acids, although more sodium hydroxide is used. Too bad they don't tell the yields of the ester and the acid but go on and hydrolyse the crude reaction products by refluxing them in ethanolic KOH for ten hours. The hydrolysis and the use of fivefold amount of NaOH in the reaction might account for the lower yields, which range from 24% to the 45% for 2-benzylidenecyclopentanone. In my opinion the method of Guillanton should work for 3-benzylidene-2-butanone too with which there is no need to hydrolyze the formed ester ethyl acetate at all. Other oxidations are also described in these articles, K2SO8 among them, haven't compared it to the one posted already in this thread though.

Here is the method of Guillanton freely translated from French, I'd appreciate if someone better at French would proofread it and tell if there are errors.

To a solution of 0.5 mole of 2-cyclopentylidenecyclopentanone in 300 ml of ethanol or methanol cooled to -10°C is added a solution of 122 ml of 15% H2O2 and 18 ml of 4M NaOH simultaneously from two addition funnels regulating the addition so that the temperature does not rise (takes approximately 20 minutes). After returning to room temperature the mixture is neutralized with 10% H2SO4. Most of the ethanol is distilled off, the mixture is extracted with ether, the organic phase is dried with Na2SO4 and the solvent distilled off, leaving the crude product behind.


Action of epoxidizing agents on 2-alkylidenecyclopentanones.
Le Guillanton, Georges.
Bulletin de la Societe Chimique de France, (8), 2871-5 (1969).  Journal written in French.
CAN 71:112467  ISSN 0037-8968
 
Abstract
Cyclic ketones I are treated with H2O2 to give d-oxoalkanoic acids RR1CHCO(CH2)3CO2H, where R and R1 and H and alkyl and aryl groups or (RR1C =) cyclopentylidene.  5-Cyclopentyl-5-oxovaleric acid is also
prepd. from the I compd. and K2S2O8 and HOOAc.




Synthesis of d-lactones.  IV.  6-Alkyl or 6-aralkyl d-lactones from cyclopentanone.
Ijima, Akie; Takahashi, Kiyoshi.
Chemical & Pharmaceutical Bulletin, 21(1), 215-19 (1973).  Journal written in French.
CAN 78:124397  ISSN 0009-2363
 
Abstract
Reaction of cyclopentanone with aldehydes or ketones RCOR1 gave cyclopentanones (I; R = H, Me, Et; R1
= Me, Et, Pr, CHMe2, Bu CH2CHMe2, n-pentyl, n-hexyl, n-heptyl, n-octyl, Ph).  Hydrogenation of I gave
II, Baeyer-Villiger oxidn. of which gave III.

Rhodium:
The references you posted are good, but they aren't fully applicable for the case we are currently discussing, as alkyl cycloalkene ketones does not suffer from the side-reaction where the double bond gets epoxidized: Post 503547 (Rhodium: "Baeyer-Villiger on unsaturated ketones", Novel Discourse)

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