Missing out on the latest research developments in ... - Sigma-Aldrich

More documents

Recommendations

Info

6 ChiPros Chiral Epoxides Oxiranes are very valuable building blocks which allow derivatization: • by forming C-X bonds (through reactions with alcohols, ammonia, amines, phenolates etc.) • or by forming new C–C bonds (through reactions with cyanide, malonates, allyl silyl reagents, metal-organic reagents, e.g. Mg, Zn, Li organyls) There are several alternative r<strong>out</strong>es towards chiral aryl-substituted epoxides, among them Jacobsen’s asymmetric epoxidation 5 or his hydrolytic kinetic resolution 6 method, Sharpless’s asymmetric epoxidation 7 using catalytic titan(IV)- isopropylate/diethyl tartrate complexes and tert-butylhydroperoxide, complemented by Shi’s reaction 8 using peroxomonosulfate with a chiral ketone as catalyst, or among the enzymatic methods, application of epoxide hydrolases, lipases or monooxygenases. The stereoselective reduction of α-chlorinated acetophenones using dehydrogenases, however, aff ords a very versatile and more cost-effi cient access to a wide range of oxiranes, including both enantiomers of styrene oxide as well as very diff erently substituted phenyl oxiranes (Scheme 3). Aldrich.com O O CH 3 R R Scheme 3: Stereoselective synthesis of oxiranes. X R OH X Base R TO ORDER: Contact your local Sigma-Aldrich offi ce (see back cover), or visit Aldrich.com/chemicalsynthesis. O O 726508 F 727253 O Cl 726699 O O 726834 Aldrich Chemistry is proud to off er ChiPros in small quantities (up to kilograms). A total of 79 products from the ChiPros portfolio are available from Aldrich Chemistry, including chiral amines, alcohols, epoxides and carboxylic acids. References: (1) http://www.chipros.com (2) Karl, U.; Simon, A. Chimica Oggi/Chemistry Today 2009, 27, 5. (3) Breuer, M.; Ditrich, K. et al. Angew. Chem. Int. Ed. 2004, 43, 788-824. (4) Blaser, H. U.; Schmidt, E. Asymmetric Catalysis on Industrial Scale, Wiley-VCH. 2004 (5) Zhang, W.; Loebach, J. L. et al. J. Am. Chem. Soc. 1990, 112, 2801-2803. (6) White, D. E.; Jacobsen, E. N. Tetrahedron: Asymmetry 2003, 14, 3633-3638. (7) (a) Katsuki, T.; Sharpless, K. B. J. Am. Chem. Soc. 1980, 102, 5974-5976. (b) Review: Hüft, E. Top. Curr. Chem. 1993, 164, 63-77. (8) (a) Wang, Z.-X.; Tu, Y. et al. J. Am. Chem. Soc. 1997, 119, 11224-11235; (b) Ager, D.; Anderson, K. et al., Org. Proc. Res. Dev. 2007, 11, 44-51; (c) Aldrich Chemfi les 2010, 3, 4-5. For a complete list of Chiral Building Blocks available from Aldrich Chemistry, visit Aldrich.com/chiralbb
New Q-Tube Pressure Reactors Q-Tubes are affordable alternatives to a microwave synthesizer and feature a safe pressure-release system (patent pending) that prevents accidental explosions due to overpressurization. Starter kits contain all items needed for immediate use. Q-Block Heating Blocks These anodized-aluminum heating blocks are designed for use with 12-mL and 35-mL Q-Tubes. The maximum working temperature is 204 °C. Blocks have a safety locking plate, safety shield, thermally stable silicone tubing, and an internal cooling channel for fast cooling (nitrogen, compressed air, or vacuum). There is also a thermocouple well for accurate temperature measurement. Q-Tube Size Cat. No. 12 mL Z567914 35 mL Z567922 Q-Tube Benefi ts: • • • • • • • • Better yield Cleaner product Reduced reaction time Higher reproducibility Scalability (up to 20 grams) Safer automatic pressure release Aff ordability Maintenance-free Q-Tube Starter Kits: Kits contain all items needed for immediate use. View accessory product listings and technical information ab<strong>out</strong> Q-Tubes on our website at sigma-aldrich.com/qtube Q-Tube Size Cat. No. 12 mL Z567671 35 mL Z567736
Page 1 and 2: Aldrich Cyclopropylboronic acid MID
Page 3 and 4: Aldrich Volume 11, Number 1 Sigma-A
Page 5: H 3C H 3CO Br 726893 NH 2 727083 72
Page 9 and 10: Iridium(I) Catalysts, Bipyridine Li
Page 11 and 12: 1.00 2.00 3.00 4.00 5.00 6.00 7.00
Page 13 and 14: Custom Packaged Reagents (CPR) To r
Page 15 and 16: generally low to moderate even when
Page 17 and 18: Subsequent to these initial studies
Page 19 and 20: Organotrifl uoroborates as Coupling
Page 21 and 22: Nano-layers of metals, semiconducti
Page 23 and 24: Thiazoles Thiazoles have been frequ
Page 25 and 26: Olefi n Metathesis Employing the se
Page 27 and 28: Unlock a smarter, greener laborator
Page 29 and 30: Specialty NMR Solvents Aldrich off
Page 31 and 32: Eliminating Static from Glove Boxes

Missing out on the latest research developments in ... - Sigma-Aldrich

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?