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Friday, 27 June 2014

Solution to Pollution By Microalgae?



 thumbnail image: Solution to Pollution By Microalgae?

Solution to Pollution By Microalgae?

Carbon dioxide concentration and light intensity influence the potential of microalgae to remove CO2 from the atmosphere
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Radical Anions for the Electron-Poor



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Radical Anions for the Electron-Poor

Anion radical coupling yields vertically fused polycyclic aromatic heterocycles
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 http://www.chemistryviews.org/details/ezine/6287491/Radical_Anions_for_the_Electron-Poor.html

Hydrophobic Catalysts



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Hydrophobic Catalysts

Introducing a hydrophobic shell enhanced the catalytic activity of core-shell catalysts in one-pot oxidation reactions
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 http://www.chemistryviews.org/details/ezine/6274191/Hydrophobic_Catalysts.html

B38 Cage: An All-Boron Fullerene Predicted



 thumbnail image: B<sub>38</sub> Cage: An All-Boron Fullerene Predicted

 

B38 Cage: An All-Boron Fullerene Predicted

Ab initio calculations predict a stable fullerene-like B38 cage cluster
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 http://www.chemistryviews.org/details/news/6295351/B38_Cage_An_All-Boron_Fullerene_Predicted.html

Friday, 20 June 2014

Recycling CO2 Under Iridium Catalysis



Recycling CO2 Under Iridium Catalysis







Enantioselective transformation of allyl carbonates into branched allyl carbamates by using amines and recycling CO2 under Ir catalysis
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http://www.chemistryviews.org/details/ezine/6282241/Recycling_CO2_Under_Iridium_Catalysis.html

Thursday, 19 June 2014

Longifolene total synthesis by Corey






File:Longifolene total synthesis by Corey.svg


Longifolene is the common (or trivial) chemical name of a naturally occurring, oily liquid hydrocarbon found primarily in the high-boiling fraction of certain pine resins. The name is derived from that of a pine species from which the compound was isolated,[1] Pinus longifolia (obsolete name for Pinus roxburghii Sarg.)[2]
Chemically, longifolene is a tricyclic sesquiterpene. This molecule is chiral, and the enantiomer commonly found in pines and other higher plants exhibits a positive optical rotation of +42.73°. The other enantiomer (optical rotation −42.73°) is found in small amounts in certain fungi and liverworts.
Longifolene is used in organic synthesis for the preparation of dilongifolylborane,[3] a chiral hydroborating agent.
Longifolene is also one of two most abundant aroma constituents of lapsang souchong tea, because the tea is smoked over pine Due to the compact tricyclic structure and lack of functional groups, Longifolene is an attractive target for research groups highlighting new synthetic methodologies. Notable syntheses are by Corey,[5][6] McMurray,[7] Johnson,[8] Oppolzer,[9] and Schultz.[10]
Chemical structure of Longifolene

Longifolene total synthesis by Corey

 

Author Elias J. Corey
Publication year 1961
Synthesis type Total synthesis
Number of steps 14 (linear)
References

 http://www.synarchive.com/syn/118

  ............image

 Total synthesis of Longifolene:

Reference:Corey, E. J.; Ohno, M.; Mitra, R. B.; Vatakencherry, P. A. J. Am. Chem. Soc. 1964, 86, 478. DOI
Keywords: Ketone → Ketal • CompE+-Ketone/Ketone+glycol • O-H → O-SO2R • Ketone → Ketal(thio) • Ketone → Alkyl-OH • Alkyl-OH → Ketone • Li-Me+Ketone • Ketone+Li-Alkyl • Dehydration → Ene • Wittig-alkyl+Ketone • Alkene → Diol-1,2 • CompNu-Alcohol/Alcohol+RSO2Cl • Pinacol • ConjAdd Enolate • Ketone enolate+Enone • Hydrogenolysis C-S • Ketone → CH2
Reagents:Wieland-Miescher • Glycol • TsOH • PPh3=CH-Me • OsO4 • TsCl, Py • LiClO4 • Carbonate, calcium • HCl, H2O • NEt3 • NaCPh3 • MeI • Thiol, (CH2)2-SH • BF3·OEt2 • AlH4-Li+ • Hydrazine • CrO3 • MeLi • SOCl2





Biosynthesis

The biosynthesis of longifolene begins with farnesyl diphosphate (1) (also called farnesyl pyrophosphate) by means of a cationic polycyclization cascade. Loss of the pyrophosphate group and cyclization by the distal alkene gives intermediate 3, which by means of a 1,3-hydride shift gives intermediate 4. After two additional cyclizations, intermediate 6 produces longifolene by a 1,2-alkyl migration.



(+)-Longifolene
Longifolene
Identifiers
CAS number 475-20-7 Yes
ChemSpider 1406720 Yes
Jmol-3D images Image 1
Properties
Molecular formula C15H24
Molar mass 204.36 g/mol
Density 0.928 g/cm3
Boiling point 254 °C (706 mm Hg)

 1,4-Methanoazulene, Junipen, (+)-Longifolene, 475-20-7, 3,3,7-trimethyl-8-methylenetricyclo[5.4.0.02,9]undecane, Kuromatsuen, Kuromatsuene 
Molecular Formula: C15H24   Molecular Weight: 204.35106
....................
The borane derivative dilongifolylborane is used in organic synthesis as a chiral hydroborating agent.[12]
  1. Naffa, P.; Ourisson, G. Bulletin de la Société chimique de France, 1954, 1410.
  2. Simonsen, J. L. J. Chem. Soc. 1920, 117, 570.
  3. Jadhav, P. K.; Brown, H. C. J. Org. Chem. 1981, 46, 2988.
  4. Shan-Shan Yao; Wen-Fei Guo; YI Lu; Yuan-Xun Jiang, "Flavor Characteristics of Lapsang Souchong and Smoked Lapsang Souchong,a Special Chinese Black Tea with Pine Smoking Process", Journal of Agricultural and Food Chemistry, Vol. 53, No.22, (2005)
  5. Corey, E. J. et al. J. Am. Chem. Soc. 1961, 83, 1251.
  6. Corey, E. J. et al. J. Am. Chem. Soc. 1964, 86, 478.
  7. McMurray, J. E.; Isser, S. J. J. Am. Chem. Soc. 1972, 94, 7132.
  8. Volkermann, R. A.; Andrews, G. C.; Johnson, W. S. J. Am. Chem. Soc. 1975, 97, 4777-4779.
  9. Oppolzer, W.; Godel, T. J. Am. Chem. Soc. 1978, 100, 2583.
  10. Schultz, A. G. et al. J. Org. Chem. 1985, 50, 915.
  11. Ho, Gregory J. Org. Chem. 2005, 70, 5139 -5143.
  12. Dev, Sukh (1981). "Aspects of longifolene chemistry. An example of another facet of natural products chemistry". Accounts of Chemical Research 14 (3): 82–88. doi:10.1021/ar00063a004.