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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.


Tuesday 17 June 2014

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

 Graphical abstract: 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

*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

Monday 16 June 2014

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

 

09224-notw8-suzuki
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

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:



'via Blog this'

Wednesday 11 June 2014

Boronic Acid Catalyzed Annulation of a Pyran Ring



Boronic Acid Catalyzed Annulation of a Pyran Ring

A route to oxygenated pyrano[3,2-a]- and pyrano[2,3-a]carbazole alkaloids
Read more

Amine Methylation Made Easy



Amine Methylation Made Easy

A mild and catalytic methylation of amines with formic acid
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Friday 30 May 2014

Visible-light-induced photocatalytic formyloxylation reactions of 3-bromooxindoles with water and DMF: the scope and mechanism

Green Chem., 2014, Advance Article
DOI: 10.1039/C4GC00647J, Paper
You-Quan Zou, Wei Guo, Feng-Lei Liu, Liang-Qiu Lu, Jia-Rong Chen, Wen-Jing Xiao
A highly efficient visible light induced formyloxylation reaction of 3-bromooxindoles was disclosed. Results of labeling experiments indicated that H2O and DMF were incorporated into the terminal 3-formyloxyoxindoles.
To cite this article before page numbers are assigned, use the DOI form of citation above.
The content of this RSS Feed (c) The Royal Society of Chemistry

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The formyloxylation reaction of 3-bromooxindoles with water and N,N-dimethylformamide (DMF) has been developed in the presence of the photoredox catalyst fac-Ir(ppy)3 under irradiation of visible light at ambient temperature. The reaction provides a straightforward approach to pharmaceutically and synthetically useful 3-formyloxyoxindoles in high yields. The mechanism of this transformation was investigated by fluorescence quenching experiments, “on–off” switching of the light source, labeling experiments, mass spectral analyses and in situ IR experiments.




ANTHONY MELVIN CRASTO
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Wednesday 14 May 2014

Oxidation from Air: New Meerwein Arylation



Oxidation from Air: New Meerwein Arylation

New carbooxygenation-type version of the Meerwein arylation allows introduction of oxygen from air by using manganese dioxide
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Building Strong Carbon Acids from 1,1-Bis(triflyl)alkadienes










Strong carbon acids set to become a useful class of organocatalysts
Read more