B38 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

Odor Code for Food Based on a Few Volatile Substances « New Drug Approvals

Odor Code for Food Based on a Few Volatile Substances « New Drug Approvals:



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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

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]

Longifolene total synthesis by Corey

 

Author	Elias J. Corey
Publication year	1961
Synthesis type	Total synthesis
Number of steps	14 (linear)
References	J. Am. Chem. Soc. 1961, 83, 1251. J. Am. Chem. Soc. 1964, 86, 478.

 http://www.synarchive.com/syn/118

  ............

 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 IUPAC name (1R,2S,7S,9S)- 3,3,7-trimethyl- 8-methylenetricyclo- [5.4.0.02,9]undecane Identifiers CAS number 475-20-7  ChemSpider 1406720  Jmol-3D images Image 1 SMILES [show] InChI [show] 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.

Altering physical properties of pharmaceutical co-crystals in a systematic manner

 

 

Altering physical properties of pharmaceutical co-crystals in a systematic manner

Christer B. Aakeröy, Safiyyah Forbes and John Desper

CrystEngComm, 2014, 16, 5870 DOI:10.1039/C4CE00206G

 

Systematic structure–property studies on a series of co-crystals of potential cancer drugs with aliphatic dicarboxylic acids were undertaken. This study reveals that systematic changes to the molecular nature of the co-crystallizing agent combined with control over the way individual building blocks are organized within the crystalline lattice makes it possible to establish predictable links between molecular structure and macroscopic physical properties, such as melting behaviour and aqueous solubility. However, it is not possible to find any notable correlation between physical properties and chemical compositions in the absence of structural consistency.

Paper

Altering physical properties of pharmaceutical co-crystals in a systematic manner

Christer B. Aakeröy,*^a   Safiyyah Forbes^a and   John Desper^a  

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*Corresponding authors

^aDepartment of Chemistry, Kansas State University, 213 CBC Building, Manhattan, USA
E-mail: aakeroy@ksu.edu;
Fax: +1 785 532 6666 ;
Tel: +1 785 532 6096

CrystEngComm, 2014,16, 5870-5877

DOI: 10.1039/C4CE00206G

C–C Coupling Repertoire Grows ... Organic Synthesis: Reaction eases addition of chiral carbon centers to aryl groups

 

REVIVAL

This new reaction combines chiral secondary and tertiary boronic esters (left) with lithiated aryls to form intermediates that rearrange upon electrophile addition, yielding aryl-alkyl coupling products.

The revival of a nearly 50-year-old technique for forming carbon-carbon bonds may help ease the synthesis of aryl derivatives, such as drug candidates.

Varinder K. Aggarwal and coworkers at the University of Bristol, in England, have taken a venerable but neglected synthesis called Zweifel olefination and made it new again (Nat. Chem. 2014, DOI: 10.1038/nchem.1971).

C–C Coupling Repertoire Grows

Organic Synthesis: Reaction eases addition of chiral carbon centers to aryl groups

 http://cen.acs.org/articles/92/i24/CC-Coupling-Repertoire-Grows.html
\SEE ALL AT

http://cen.acs.org/articles/92/i24/CC-Coupling-Repertoire-Grows.html


 BRAZIL WORLDCUP WEEK 2014

A TWO-STEP TANDEM REACTION TO PREPARE HYDROXAMIC ACIDS DIRECTLY FROM ALCOHOLS | ORGANIC CHEMISTRY SELECT

A TWO-STEP TANDEM REACTION TO PREPARE HYDROXAMIC ACIDS DIRECTLY FROM ALCOHOLS | ORGANIC CHEMISTRY SELECT:



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