Author Topic: New synthesis of phenylacetones  (Read 1412 times)

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psychokitty

  • Guest
New synthesis of phenylacetones
« on: September 14, 2004, 09:12:00 AM »
This one looks like a variation of the thallium nitrate rearrangement of B-methylstyrenes to that of a-arylketones:


Lego

  • Guest
Phenylacetones from alpha-methyl-styrenes
« Reply #1 on: September 14, 2004, 11:09:00 AM »
Oxidative rearrangements of arylalkenes with [hydroxy(tosyloxy)iodo]benzene in 95% methanol: a general, regiospecific synthesis of alpha-aryl ketones
Michael W. Justik and Gerald F. Koser
Tet. Lett., 2004, 45(32), 6159-6163
DOI:

10.1016/j.tetlet.2004.06.029


Fulltext:

Post 531247

(psychokitty: "New synthesis of phenylacetones", Novel Discourse)


Abstract: The treatment of arylalkenes with [hydroxy(tosyloxy)iodo]benzene in 95% methanol affords the corresponding alpha-aryl ketones. This oxidative rearrangement is general for acyclic and cyclic arylalkenes and permits regioselective syntheses of isomeric alpha-phenyl ketone pairs.






Synthesis of [hydroxy(tosyloxy)iodo]benzene:

Hypervalent Organoiodine. Reactions of Silver Arylsulfonates with Iodosobenzene Dichloride
Gerald F. Koser, Richard H. Wettach
J. Org. Chem., 1977, 42, 1476-1478




Iodosobenzene diacetate (1)

Reaction of 1 with p-Toluenesulfonic Acid in CH3CN. p-Toluenesulfonic acid monohydrate (7.61 g, 40 mmol), dissolved in a minimum quantity of CH3CN, was added to a solution/suspension of 1 (6.44 g, 20 mmol) in CH3CN (45 mL) at room temperature. The reaction mixture immediately cleared and turned yellow and, upon standing at room temperature, gave phenylhydroxyltosyloxyiodine (4a) as fine white needles with a yellowish hue. Two crops were isolated, yield 7.62 g (93%). The crude product was washed with acetone (removes p-toluenesulfonic acid) and ether (removes acetic acid) and dried: mp 135-138 °C




Synthesis of iodosobenzene diacetate

Easy Preparation of (Diacetoxyiodo)arenes from Iodoarenes with Sodium Percarbonate as the Oxidant
Agnieszka Zielinska and Lech Skulski

Molecules, 2002, 7(11), 806-809.pdf

(http://www.mdpi.org/molecules/papers/71100806.pdf)

Sodium percarbonate (18.4 mmol, 330% excess) was slowly added portionwise to a stirred mixture of Ac2O (7.0 mL), AcOH (5.8 mL), and CH2Cl2 (40 mL). The stirring was continued for 1.5 h at <= 30°C. An appropriate iodoarene was then added (6.4 mmol), and the reaction mixture was then stirred at 40°C for 5 h. After cooling, the precipitated CH3COONa was collected by filtration under reduced pressure, washed with CH2Cl2 (2 x 15 mL) and discarded. The filtrates were evaporated under vacuum, and cold (0-5 °C) 10% aq. CH3COOH (15 mL) was rapidly added. The flask was left in a cooler for a few hours. The colorless crystals formed were collected by filtration, washed with hexane and air-dried in the dark. Most of those crude products thus obtained need not be further purified, as they were 96-99% pure, according to iodometric analysis [6]. When necessary, the crude products were recrystallized from AcOEt/Ac2O (9:1, v/v) [2]. They should be stored in the dark, preferably in a cooler. See Table 1 for more details. Under these conditions 4-iodotoluene and 4-chloroiodobenzene were unexpectedly oxidized to the corresponding iodylarenes (recrystallized from boiling water).

[2] Kazmierczak, P.; Skulski, L. A Simple, Two-Step Conversion of Various Iodoarenes to (Diacetoxyiodo)arenes with Chromium(VI) Oxide as the Oxidant. Synthesis 1998, 1721-1723, and references therein.
[6] Lucas, H. J.; Kennedy, E. R.; Formo, M. W. Org. Synth. 1942, 22, 70.




For a synthesis without acetic anhydride but with peracetic acid/acetic acid, see:

Organic Syntheses, CV 5, 660

(http://www.orgsyn.org/orgsyn/prep.asp?prep=cv5p0660)


Rhodium

  • Guest
alpha-Methylstyrenes to P2P
« Reply #2 on: September 14, 2004, 04:14:00 PM »
Interesting - this is very similar to the patent I discovered the other day:

Post 530316

(Rhodium: "Novel route to P2P from alpha-methylstyrene", Novel Discourse)