Baran Group Meeting Debora Chiodi Rhenium Chemistry 10/24/20 Applications: Selected books and reviews: Re(s) Properties of rhenium: • High-temperature superalloys (e.g., jet engine • “Rhenium: Properties, Uses • Appearance: silver-gray parts, aircraft turbine blades) and Occurrence”, 2017, Eric • d7 transition metal • Pt–Re cat. for lead-free, high-octane gasoline James, Nova Science • Electronic configuration: [Xe] 4f14 5d5 6s2 • Analysis of meteorites to determine their origin Publishers, Inc. (book) • Oxidation states: from –1 to +7 (e.g., different solar system) • Eur. J. Org. Chem. 2017, • Most common oxidation states in catalysis: • Therapeutics and diagnostics for nuclear medicine 3549–3564. (review) +1, +3, +5, +7 • Catalysts in organic chemistry • Chem. Rev. 2011, 111, • One of the rarest elements in the Earth's crust 1938–1953. (review) • "Rhenium-oxo and rhenium- (average concentration 0.5–1 ppb) peroxo complexes in catalytic • 0.2% Re present in molybdenite (main source) 185 187 oxidations." Springer, Berlin, • Isotopes: Re and Re Heidelberg, 2000. (book) • Melting point = 3180°C, it is the highest melting metal • “Inorganic Syntheses”, after tungsten (3380°C) volume XVII, 1997, chapter molybdenite iron meteorite Pratt & Whitney turbofan engine (U.S. airforce) 31. (book) Historical Timeline 1908 First discovery by Masataka Ogawa 1910 Henry Mosley postulated the existence of 2 missing elements in the periodic table (no. 43 and 75) 1919 Masataka Ogawa isolated Re(s) for the first time Walter Noddack, Ida Noddack, & Otto Berg chalcopyrite 1925 named the element after the river Rhein 1927 120 mg of pure Re were extracted 1928 1 g Re extracted from 660 kg of molybdenite 1928-1930 1st industrial production of Re 1929-1930 MW = 188.71 g/mol accepted by German Atomic Weight Commission 1948 Re production started in USSR 1960 Re world production = 10 tons 75% Re metal in USA was employed 1968 in R&D of refractory metal alloys First organo-rhenium(VII) 1975 synthesis by Mertis and Wilkinson 1979 First synthesis of MTO by Beattie and Jones (low yield) chalcopyrite ore (in Chile) Re first catalytic application: optimized 1987 synthesis of MTO by Herrman First application of high valent oxo-Re(V) 2003 in organic chemistry by Toste 2005 First application of low valent Re in organic chemistry by Takai and Kuninobu 2008 77% Re in USA employed for alloys Production of rhenium during copper extraction Walter and Ida Naddock 1 Baran Group Meeting Debora Chiodi Rhenium Chemistry 10/24/20 Most commonly encountered Re compounds Features of rhenium Oxidations using Re(V) and Re(VII) • Manganese-group transition metal (Group 7) O prices from • Characteristics of both early and late transition metal species cat. MTO R • Lower electronegativity than late transition metals such as Rh, Ru, Pd, etc. R1 R R1 H2O2 +7 • Re–X (X = C, N, O) bonds are more polarized than the corresponding O Me O ⎤ M–X bonds of late transition metals under the same conditions O O byproducts: O • Re–X (X = C, N, O) bond has stronger nucleophilicity than M–X bonds of Re K Re Re O O Re late transition metals O O O O O O + 1 O O O O • Also has a similar reactivity to late-transition metal complexes (oxidative R OH R OH addition, reductive elimination, and -H elimination, etc.) MTO β • Wide range of oxidation states ranging from –1 to +7 J. Org. Chem. 1995, 60, 7728–7732. 2 g $327.00 5 g $188.00 1 g $197.00 2 Some examples of Re complex synthesis R R cat. MTO O R R2 1 3 H O +6 Me OSnMe3 R R 2 2 1 3 O PPh3 [O] number not R R I O very common, THF Re Re2O7 + Me4Sn Re + Re Angew. Chem. Int. Ed. 1991, 30, Re O I more frequent O O O O 1638–1641. O O PPh as intermediate O O Inorg. Chem. 1998, 37, 467–472. 3 Angew. Chem. Int. Ed. 1988, 27, 394. Inorg. Chem. Commun. 1 g $201.00 O 2015, 51, 83–86. Me Me Me cat. KReO4 1 2 H H + H2O2 O + H2O2 O O R R H O Re O Re Re 2 2 R1 R2 O O - H2O O - H2O O O +5 O Ph O O O Chem. Commun. 2015, 51, 3399–3402. O O Ph Cl Cl Cl PPh Cl P Re Re 3 Re J. Organomet. Chem. 1995, 500, 149. Cl SMe Cl PPh Cl cat. oxo-Re(V) 2 3 P Ph O OPPh3 Cl Cl ⎤ Ph TBHP Ph O O O Ph 37% HCl, EtOH Cl PPh3 CHCl Cl P 1 g $225.00 1 g $74.40 1 g $344.00 Re K Re 3 Re Cl PPh Cl Catalyst: O O PPh3, reflux 3 dppm, reflux P Ph O 30 min, Ar Cl 2 h, Ar Cl Ph O L= MeCN +3 H O O N PPh Cl N PPh3 N Cl 3 Cl PPh dry PhMe Cl Re Ph N Cl Cl Re 3 Re N N Re Cl SMe2 O L Re Re Cl PPh3 37% HCl Cl NCMe OPPh tBu O O Cl Cl Cl Cl Cl DMSO, 12 h, rt 3 PPh3 tBu PPh3 Inorg. Chem. 1998, 37, 4979–4985. tBu tBu 1 g $409.00 1 g $248.00 J. Chem. Soc. 1962, 4019–4033. or Inorg. Chim. Acta 1993, 204, 63–71. “Inorganic Syntheses”, Volume XVII, 1997, Chapter 31. O Ph PPh Ph +1 Br Br 3 Cl P OC OC CO OC N N 250 bar, neat, 250 °C Re Re CO Re Re Re2O7 + 17 CO Re2(CO)10 + 7 CO2 Cl OC OC CO Cl CO P dist. hexane, rt, N2, 30 min Cl Ph thf CO PPh Re2(CO)10 + Br2 2 ReBr(CO) Ph 2 3 5 500 mg $218.00 1 g $147.00 "Pentacarbonylrhenium Halides”, Inorganic Syntheses. 1990, 28, 154–159. Cat. Commun. 2009, 10, 720–724. "Organo-Transition Metal Chemistry: A Personal View”, 2009, p.108. Inorg. Chem. 2016, 55, 5973−5982. 2 Baran Group Meeting Debora Chiodi Rhenium Chemistry 10/24/20 O O Oxidations using Re(VII), Re(V), and Re(III) Angew. Chem. Int. Ed. Benzene to benzoquinone: Me Me MTO epoxidation 1991, 30, 1638–1641. MTO, H O Me Inorg. Chem. 1998, 37, 2 2 also: mechanism: O + H2O Me 467–472. AcOH Me Me Men Me + H O n Me Me 2 O vitamin K3 O Me H2O Me Me Me H O H2O H H OH O O 2 O Me O O O Re Me O Re Me O Me Me O O O Re Me Me or O Me O Me O O Me Me O Me Me Me Me O Me Me Re O O repeated twice in order to get the quinone O 2 Me Inorg. Chim. Acta 1998, 270, 55–59. J. Org. Chem. 1994, 59, 8281–8283. Me Me Me OH2 Me O Angew. Chem. Int. Ed. 1995, 33, 2475–2477. Me O O Me Me Re H O Re Me O O O H O 2 O Benzylic 2 2 H2O2 O Me ReOCl3(OPPh3)(SMe2) (5 mol %) Me O O oxidation: TBHP (2 equiv.), 90°C 3 1 ACS Catal. 2012, 2, 163−167. Miscellaneous oxidations using MTO: Pyridine N MTO (0.5 mol%) J. Org. Chem. R O oxidation: X + RCOOH X 1998, 63, HO cat. MTO SH cat. MTO 30% aq. H O (2 equiv.) N+ OH S N 2 2 1740–1741. HO rt, CH Cl - O H2O2 SH DMSO S 2 2 O O Organometallics 1996, 15, 3543–3549. Inorg. Chem. 1999, 38, 1040–1041. Reductions: Re(V) and Re(VII) Deoxygenation of carbonyls and alcohols: OH cat. MTO Me O Me cat. MTO O H2O2 Reaction conditions: 3-pentanol, cat. ReOCl3(SMe2)(OPPh3), 170°C H2O2 OH 1 1 H R R tBuOH R R Me Me tBuOH H + Me R, R1 = alkyl, aryl 19–95% H 98% MeO MeO MeO Me Tetrahedron Lett. 1995, 36, 6415-6418; Tetrahedron Lett. 1996, 37, 6487–6490. Cl O Cl OH Cl Cl O Baeyer–Villiger oxidation using Re(V) and Re(III): Me H O PPh3 + O (by- Re catalysts: N N cat. [Re] Cl Re Cl Cl Cl product) O Ph Cl Cl O H O N N n 2 2 n PPh3 ChemCatChem 2015, 7, 1177–1183. Green Chem. 2016, 18, 2675–2681. O III O O Re SO cat. [Re] N N 3 PPh3 Stereospecific epoxide deoxygenation: Org. Lett. 2015, 17, 3346–3349. R1 1 N Cl O O O R1 R R H2O2 R O N N Re cat. Re2O7 cat. Re2O7 N Cl Cl R R1 App. Cat. A: Gen. 2012, 443, 27–32. R 1 P(OPh)3, 1 P(OPh) , N N R R R 3 R Inorg. Chim. Acta 2017, 455, 390–397. PPh3 toluene, 100°C toluene, 100°C 3 Baran Group Meeting Debora Chiodi Rhenium Chemistry 10/24/20 Reductions: Re(V) and Re(VII) Example 1: OH R1 O An alternative to the Corey– HO OH cat. MTO, 2° ROH 1) 1.5 equiv. Me2PhSiH, 1 5 mol% 3 R1 Winter olefination: 140°C R yield% = 71–90% R R1 R DCM, rt 2 ee% = 77–93% R2 2) 1 equiv. TBAF R RCOOH + HO OH 3 R3 Me R1COOH R Me O 1 R R1 OH Example 2: One-pot Meyer–Schuster rearrangement / asymmetric reduction HO OH Re R O 1 O Re R Me Me 3 mol% O O OH Ph O Ph OH O 4 O 4 2.5 mol% 2 semicorrine ligand 1 R R1 R H O Ph 2 2 dioxane R Ph Ph R 2 equiv.