(E)-tert-butyl 3-(4-cyanophenyl)acrylate

(E)-tert-butyl 3-(4-cyanophenyl)acrylate

A flame-dried three-neck round-bottom flask equipped with a magnetic stirring bar, a thermometer, an addition funnel and a nitrogen inlet was charged with NaH (3.96 g, 94.7 mmol) and anhydrous THF (120 mL). Tertbutyldiethylphosphono acetate (23.2 mL, 94.7 mmol) dissolved in anhydrous THF (20 mL) was added dropwise via the addition funnel over a period of 30 min. After the completion of addition, the reaction mixture was stirred at rt for another 30 min. A solution of 4- cyanobenzaldehyde (1 1 .3 g, 86.1 mmol) dissolved in anhydrous THF (20 mL) was added to the reaction mixture dropwise via the addition funnel over a period of 30 min. After the end of the addition, the reaction mixture was stirred at rt for 1 h, then diluted with MTBE (200 mL) and sat. NH₄CI (150 mL). The organic layer was separated, washed with 25 mL of H₂0 and 25 mL of sat. NH₄CI, dried over MgS0₄, filtered and evaporated to dryness to give 20.0 g Intermediate G as a solid (100%). 

¹H NMR (400 MHz, CDCI₃) δ ppm 1 .56 (s, 9H) 6.47 (d, J=16 Hz, 1 H) 7.58 (d, J=16 Hz, 1 H) 7.61 (d, J=8 Hz, 2H) 7.68 (d, J=8 Hz, 2H)

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Despite the cold weather, public came and enjoyed different activities. The famous chef, Paul Svensson who works in one of the fanciest and most famous …

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(1 S, 2S)-2-(4-Bromo-phenyl)-cyclopropanecarboxylic acid

(1 S, 2S)-2-(4-Bromo-phenyl)-cyclopropanecarboxylic acid

To a stirred solution of (trans)-2-(4-bromophenyl)cyclopropanecarboxylic acid (6.52 g, 27.04 mmol), which can be prepared in accordance with the process set forth on page 82 of WO 2009/024823, in 400 ml of EtOH was added a solution of (R)-(+)-1 -(1 -Naphthyl)ethylamine (4.63g, 4.37 ml_, 27.04 mmol), in 1 00 ml of EtOH followed by 25 ml of H₂0. This was stirred at rt for about 4 h. The solid was collected by filtration and washed with 40 ml of cold EtOH/H₂0 (20/1 ) providing 3.18 grams of salt as a white solid (58 % recovery) equivalent to 1 .86 g of free acid. This was taken up in 2 N NaOH and extracted 5Xs with EtOAc. The aq. phase was placed on a rotary evaporator to remove the remaining EtOAc. The resulting clear solution was transferred to an erlenmeyer flask, cooled in an ice bath, and cone. HCI was added dropwise while stirring to pH 4. The resulting solid was collected by filtration providing 1 .63 g of Intermediate R. The product was analyzed by chiral SFC (UV detection) using isocratic method (mobile phase: 25% MeOH with 0.1 % DMEA, supercritical C0₂) on ChiralPak AD-H, 10 x 250 mm, 5 μιη particle size, giving an enantiomeric purity of >95%, Rt 3.88 min (isomer 1 ) and 4.79 min (isomer 2). 

¹ H NM R (400 MHz, CDCI₃) δ ppm 1 .37 (ddd, J=8.20, 6.64, 4.69 Hz, 1 H), 1 .67 (ddd, J=9.28, 5.08, 4.79 Hz, 1 H), 1 .87 (ddd, J=8.50, 4.69, 4.39 Hz, 1 H), 2.48-2.63 (m, 1 H), 6.87-7.06 (m, 2H), 7.37-7.46 (m, 2H).

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Cabocation NMR

The carbocations (2) and (3) only differ in the positions of electrons, so they are resonance forms of the same ion, and can be described as a non-classical carbocation. NMR evidence for the non-classical nature of such cations is given in March (6th ed.), pp. 1582–1583.

Wagner-Meerwein shift

Camphene hydrochloride–isobornyl chloride rearrangment

J. Org. Chem. (1999) 64, 60–64

In the presence of a Lewis acid catalyst, camphene hydrochloride (1) rearranges to isobornyl chloride (2).



The mechanism is believed to involve the following steps:

• the Lewis acid catalyst abstracts chloride from camphene hydrochloride (1), leaving behind a tertiary carbocation (2)
• the tertiary carbocation (2) rearranges to a secondary carbocation (3) by a [1,2]-alkyl shift
• a chloride ion adds to the secondary carbocation (3), forming isoborny chloride (4)

The OH of 3-cyclohexenol can be removed using superacid:

The NMR of the cation can be recorded, at -80°:

The central 141.9 ppm carbon is typical of a double bond.

The 224.4 ppms are highly deshielded, but not as much as a localized carbocation, which would be around 330 ppm:

Anti-cyclooctadiene derivative 15: 


1H NMR (600 MHz, CDCl3) δ 6.45 (dd, 2H, J1 = 1.84, J2 = 7.80 Hz), 6.41 (d, 2H, J = 1.84 Hz), 6.31 (d, 2H, J = 7.80 Hz), 6.05–6.00 (m, 2H), 5.94–5.88 (m, 2H), 4.89–4.82 (m, 2H), 3.39–3.29 (m, 2H), 3.19–3.09 (m, 2H), 3.06–2.96 (m, 2H), 2.92–2.83 (m, 2H), 2.78–2.68 (m, 2H), 2.34–2.26 (m, 2H) ppm;


13C NMR (150.9 MHz, CDCl3) δ 143.6, 140.2, 139.4, 136.6 (+), 132.9 (+), 131.4 (+), 130.7 (+), 128.8 (+), 48.5 (+), 36.3 (−), 33.3 (−), 27.2 (−) ppm; 


MS (EI, 70 eV) m/z (%): 312 (19), 157 (33), 156 (40), 155 (100), 142 (12), 141 (55), 129 (18), 128 (22), 115 (17).

Interestingly, all three isomers of 10 (trans,trans-, cis,trans- and cis,cis-) under the above irradiation conditions furnish the same product: 16. It is hence likely that a rapid photoequilibration process precedes the ring closure to the final product.

Attempts to crystallize 14 from boiling ethanol led to a mixture of 14 and the cyclooctadiene derivative 15, which was separable by column chromatography. The divinylcyclobutane derivative 14 was completely converted into the cyclooctadiene derivative 15 within half an hour in boiling ethanol. The structure of 15 was confirmed by single-crystal X-ray analysis

Intraannular photoreactions in pseudo-geminally substituted [2.2]paracyclophanes

Henning Hopf1, Vitaly Raev1 and Peter G. Jones2

1Institut für Organische Chemie, Technische Universität Braunschweig, Hagenring 30, D-38106 Braunschweig, Germany, Fax: +49 531 / 391 5388
2Institut für Anorganische und Analytische Chemie, Technische Universität Braunschweig, Hagenring 30, D-38106 Braunschweig, Germany, Fax: +49 531 / 391 5387

 Author email       Corresponding author email     

This article is part of the Thematic Series "Photocycloadditions and photorearrangements". Photoactive cyclophanes, part 6. For part 5 see [1].

Guest Editor: A. G. Griesbeck

Beilstein J. Org. Chem. 2011, 7, 658–667.

http://www.beilstein-journals.org/bjoc/single/articleFullText.htm?publicId=1860-5397-7-78


p.jones@tu-bs.de, h.hopf@tu-bs.de


Braunschweig, Germany, 

Braunschweig Alstom LHB GT6 tram no. 8165 at Lincolnsiedlung.

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