Hai Dao Baran Group Meeting Nitroso and Nitro Compounds 11/22/2014 Part 1. Introduction Nitro Compounds

O D(Kcal/mol) d (Å) NO NO+ Ph NO Ph N cellular signaling 2 N O N O OH CH3−NO 40 1.48 molecule in mammals a nitro compound a nitronic acid nitric oxide b.p = 100 oC (8 mm) o CH3−NO2 57 1.47 nitrosonium m.p = 84 C ion (pKa = 2−6) CH3−NH2 79 1.47 IR: υ(N=O): 1621-1539 cm-1 CH3−I 56 Nitro group is an EWG (both −I and −M) Reaction Modes Nitro group is a "sink" of electron Nitroso vs. olefin: e Diels-Alder reaction: as dienophiles Nu O NO − NO Ene reaction 3 2 2 + N R h NO2 O e Cope rearrangement υ O O Nu R2 N N N R1 N Nitroso vs. carbonyl R1 O O O O O N O O hυ Nucleophilic addition [O] N R2 R O O R3 Other reaction modes nitrite Radical addition high temp low temp nitrolium EWG [H] ion brown color less ion Redox reaction Photochemical reaction Nitroso Compounds (C-Nitroso Compounds) R2 R1 O R3 R1 Synthesis of C-Nitroso Compounds 2 O R1 R 2 N R3 3 R 3 N R N R N 3 + R2 2 R N O With NO sources: NaNO2/HCl, NOBF4, NOCl, NOSbF6, RONO... 1 R O R R1 O Substitution trans-dimer monomer: blue color cis-dimer colorless colorless R R NOBF OH 4 - R = OH, OMe, Me, NR2, NHR N R2 R3 = H or NaNO /HCl - para-selectivity ΔG = 10 Kcal mol-1 Me 2 Me R1 NO oxime R rate determining step Blue color: n π∗ absorption band 630-790 nm IR: υ(N=O): 1621-1539 cm-1, dimer υ(N−O): 1300 (cis), 1200 (trans) cm-1 + 1 Me H NMR (α-C-H) δ = 4 ppm: nitroso is an EWG ON H 3 Kochi et al. J. Org. Chem. 1994, 59, 5573–5586. R = H: unstable (favor the oxime form), in situ generation Wheland intermediate Chem. Rev. 2004, 104, 3315–3340. Hai Dao Baran Group Meeting Nitroso and Nitro Compounds 11/22/2014

Other external [NO] sources OMe OMe Elimination reactions H Me N Me NOBF , DCM CH2OH Ts OTBDMS O O 4 O O 1. NO NHAc DEAD, Ph P NHAc 95% 3 O O O NO O 2. CsF 90% OMe O MeO Me MeO Me O Org. Lett. 2008, 10, 2259. Aust. J. Chem. 1994, 47, 1483–1508. Metal-NO complexes via NAc O O [Co(Cp)(NO)] NO 2 N N NO (Cp)Co Co(Cp) 68% N N Br Me H H NO O O Organometallics 1983, 2, 787. tBuLi Me Internal [NO] sources H Me AmNONO H Me Barton reaction and other reactions with NO H H H NO N H N O NO Me NO Me Me Me Me HN tBu t tBu O H h Bu Me H NOH Me H Me Me υ Me Me HCl H H H 30-40% dimer 75% H tBu t tBu H H H Bu H H N N N Can. J. Chem. 1978, 56, 2665. Lyconadin B Oxidation reactions HO O CH OH Fukuyama et al. J. Am. Chem. Soc. 2013, 135, 3243. HO O CH OH 2 2 mCPBA Addition reactions to C=C double bonds 47% HO OH Fe(acac) (10 mol%) NO HO OH 3 NO 2 BzO NH3 Cl PhSiH , BuONO BzO Me Me Me 3 2 Me 64% Cl2, CHCl3 Cl , CHCl Mukaiyama et al. Chemistry Letters 1992, 1137–1140. 2 3 Na2CO3 Cl NO F F 69% 42% NOCl, CsCl ON NO NOH F F Cl i F C F3C Pr i iPr 3 91% Cl Pr F F synthesis 2006, 3819. J Fluorine Chem., 1984, 26, 87. Reduction from Nitro group Hai Dao Baran Group Meeting Nitroso and Nitro Compounds 11/22/2014

Ene reaction OH Reaction of C-Nitroso Compounds O NHOH N Hetero Diels-Alder reaction N O N CO CO Br Me nPr NIO O 4 4 O Br Me Me Bu4NIO4 O Al(Hg) O 80% O 91% O O + O O O O Me O N then Δ O dl-crinane R Me 85% 2 steps Keck et al. J. Am. Chem. Soc. 1981, 103, 3173. O Br Me OH OAc CuCl (5 mol%) O NHOH OH OAc OAc OH Py (12 mol%) Cbz = O + N + NCbz O RNHOH Br CbzNHOH THF, air, rt OH OH O O O Me Me 87% OH Me Me Me 9:1 NH NH O O J. Read de Alaniz, J. Am. Chem. Soc. 2011, 133, 10430–10433. 1 O O Regioselectivity nitroso compound vs. O2 and triazolinedione (TDA) Lycoricidine with ArNO

Hudlicky, et al. J. Am. Chem. Soc. 1992, 114 , 9694–9696.

Me HO Mo(CO)6 OH N O NaBH4 Br H O NH 70% BocN N HH BocHN NH

O agelastatin A Krebs et al. Chem. Rev. 2003, 103, 4131–4146. Tanaka et al. Org. Lett. 2008, 10, 5457–5460. Cope reaction OTMS OTMS Cl NO F TBDMSO 1. AcOH OTBDMS OTBDMS F F 1. LDA Et3N O 2. BzCl H + 2. TMSCl 60% CO2Me N N OBz 72% 3. AmONO CO2Me N overall MeO TiCl O O CO2Me 4 MeO N H [H-NO equivalent] O Schlosser, et al. Tetrahedron 1993, 49, 1445. Zakarian et al. J. Am. Chem. Soc. 2006, 128, 5356–5357. Hai Dao Baran Group Meeting Nitroso and Nitro Compounds 11/22/2014

O-Nitroso aldol vs. N-nitroso aldol reaction Other reactions PhNO HO alkylnitroso (1-chloro-1-nitrosoalkanes): N selectivity with enolate B(pin) then H2O2 Ni(cod) O Me Hex 1. NaHMDS B2(pin)2 O Cl NO OH Me N B(pin) 2. Me O H2O2 Hex OH N Me Hex Hex N O H OH 3. HCl N O S O Morken et al. Org. Lett. 2010, 12, 3796. 80% S O Me piridinine O Me O Me Me Davison et al. J. Chem. Soc. Perkin Trans. 1, 2002, 1494. TMSO O PhNO O TMSCl HOAc Aldol reaction (acyl and arylnitroso compound): steric and electronic factors alotaketal A O FeCl 60% OH O O O 3 Cu(OTf)2 (10 mol%) MeMgBr + O (RR)-PhBox Me Me SAr SAr Me tBuO NHOH MnO2 (5 equiv) ONHBoc MeO DCM, rt Yang et al. Org. Lett 2010, 12, 5072–5074. 61%, 97% ee MeO CO Me slow addition Mo(CO) H 2 6 CO2Me O O PhNO O O NHCO Me 2 ZrCl4 NHCO2Me OMe AgTFA SAr OH N 82% OH H N MeO MeOH MeO H (+)-Kjelmanianone Baran et al. J. Am. Chem. Soc. 2006, 128, 8678–8693. Yamamoto et al. J. Am. Chem. Soc. 2012, 134, 18566. Other nitroso compounds O O CuCl (5 mol%) O O OH CuOTf (5 mol%) Furoxans + NBoc Me OEt t Me BuO NHOH MeOH, air, rt N N Me Me CO2Et Δ O 79% O Read de Alaniz, et al. J. Am. Chem. Soc. 2012, 134, 18948–18951. O N N Reaction with radical O furoxan Ph Ph O-Nitroso compounds (nitrite compounds) Ph Ph Ph Ph Ph Ph PhNO Ph Δ or hυ O Me HONO Me N N N O NO Ph Me OH Me O N esterification Adam et al. Tetrahedron Letters 1991, 32, 4283. amyl nitrite Hai Dao Baran Group Meeting Nitroso and Nitro Compounds 11/22/2014

R N-Nitrosoamine (secondary amine derivatives) R R HI AgNO2 HONO R NO blue R OH R I R NO color ON HN 2 HN N or P+I2 R NO2 NaNO2 CN CN Pseudonitrolic acid HCl CN R R HI R AgNO2 R NR: colorless Fischer–Hepp R OH or P+I R I rearrangement 2 NO Nitration with nitro radical D'Amico et al. J. Am. Chem. Soc. 1959, 81, 5957–5963. S-Nitrosothiols (thionitrites) AgNO2 NO TEMPO 2 S O Me Me DCE O O N O - NO is an important cellular Me Me signaling molecule 70 oC HO N OH - GSNO: endogenous NO carriers 69% Maiti et al. J. Am. Chem. Soc. 2013, 135, 3355 H NH O and donors 2 Oxidation of amines, oximes or azides NO S-Nitrosoglutathione (GSNO) 2 I O O O HONO O 1. NaN3 O + RSH RSNO RSSR 2NO N OCH2CCl3 O 2. PPh OC deeply colored N OCH CCl 3 CO R'SH OC 2 3 3. O compounds CO 3 R'SNO 50%

Synthesis of nitro compounds Corey et al. J. Am. Chem. Soc. 1984, 106, 3682–3683. + Nitration with NO2 OH Reaction of nitro compounds OH OH NaNO3 H2SO4 O2N Henry reaction, Michael reaction: see ref + 100g scale Nef reaction, reduction: see ref Br Br Br Radical chain nucleophilic substitution (SRN1) NO2 CH NO p-pdt: recrystalization in CHCl3 I 2 2 hυ - + Nitration with NO2 Na CH2NO2 NaCH COCH AgNO : Victor-Meyer reaction, NaNO : Kornblum reaction, KNO 2 3 2 2 2 68% Victor-Meyer test (primary vs. secondary vs. tertiary alcohol) I CH NO NOH NONa 2 2 HI AgNO2 HONO NaOH CH2NO2 R OH R I R NO2 or P+I2 R NO2 R NO red 2 nitrolic acid color Rossi et al. J. Org. Chem. 1999, 64, 5826. Hai Dao Baran Group Meeting Nitroso and Nitro Compounds 11/22/2014

CH2I CH Co(dmgH) py Cycloaddition Me Me 2 2 hυ O O O O py(dmgH)Co O O N O O O OR Na NaCH2NO2 O Me O O N O Me KO H 82% then AcOH NO OiPr O Me O Cl 2 Me 76% O OR OiPr O OiPr O O Me CH2CH2NO2 Me MAPh Me R O O O O O O O N N O Me RCo(dmgH)2py = H Co H MAPh: methylaluminum bis(2,6-diphenylphenoxide) O N N O O O Me Py O O OR N O N N i HO Me PrO2C H 1. [H] HO Branchaud et al. Tetrahedron Letters 1991, 32, 3639. H 2. Ni, H H H H 74% H 2 H H H OH O O Elimination of NO2 HO O HO (-)-rosmarinecine NO2 is a good leaving group Denmark et al. J. Am. Chem. Soc. 1996, 118 , 8266. O O O O K 77% + N Ph O N N Ph t t tBu Bu Bu Ph NO2 N O PPh3AuTf2 N NO2 nitrone O Russ. Chem. Bull. 1996, 45, 856. O O R1 NO2 base O R1 68% + 3 HN O R 2 Au N R O R2 Barton-Zard C N 2 pyrrole synthesis N R O O removal of NO2 under radical conditions Liu et al. J. Am. Chem. Soc. N Au 2011, 133, 1769. BzO BzO NO2 N NHBz Au O NO Nu BzO 2 Nu Bu3SnH Photochemistry N N 78% AIBN meta-activation OHCO 48% OBn NO2 NO NO2 OHCO OBn 2 h OHCO OBn υ NaOMe, MeOH N or N NH * 2 14 SN2Ar NO2 O Me OMe OMe Pd/C; H2 HO OMe O14Me Φm = 0.21 vs Φp = 0.016 OMe 93% N N - direct substitution of the triplet state: meta-activation vs. SNAr Zanirato et al. - depend on: nucleophiles, solvent system Tetrahedron Letters 1996, 37, 7599. HO OH (-)-aristeromycin Havinga et al. J. Am. Chem. Soc. 1981, 103, 7257–7262. Hai Dao Baran Group Meeting Nitroso and Nitro Compounds 11/22/2014

NHnHex activation of nitronic acid n NO HexNH2 Me 2 NO2 O N OMe hυ 2 Me OH * N O SN2Ar hυ NaOMe OMe NO OMe 2 AcO MeOH OMe N H O2N N 78% 17% hυ − * OMe SR N1Ar − * OMe SR N1Ar : radical ion pair via ET from amine to nitro O N O O NO2 hυ NO2 N h O NaOH, H2O υ o and p < 20% OH 75% OH N N H Photo-Smiles reaction H Oxman et al. J. Am. Chem. Soc. 1980, 102, 4848. hυ

Activation of nitro group O O CH2 OH N OH N N O HAT O hυ 73% MeOH tBu tBu tBu Döpp et al. Eur. J. Org. Chem. 1979, 1979, 554–563.

OAc OMe OAc OMe Me O O hυ O Me O AcO AcO AcO O 60% AcO HO OAc O OAc O O O2N Ar

Collins et al. J. Chem. Soc., Perkin Trans. 1 1983, 1879