M.C. White, Chem 153 Silylformylation-214 Week of octo ber 29. 2002 alkenes Intramolecular silylformylation-allylsilylation lighton JACS 2000(122)8587 H,0 Nahco Meoh i-Pr benzene.60℃C Leighton ACIEE 2001(40)2915 1. TBAF 000 psi CO, H Aco i-Pr benzene 60C 70% overall yield OHOHOH OTIPS OPMB 2.H202, NaHCO3 55%overall yield Schreiber intermediate to Mycoti Meoh lighton JACS 2001(123)341 Schreiber JACS 1993(115)3360
M.C. White, Chem 153 Silylformylation -214- Week of October 29, 2002 Intramolecular silylformylation-allylsilylation i-Pr O Si H O Rh(I) O CO CO 1 mol% 1000 psi CO, benzene, 60oC i-Pr O Si O H i-Pr O Si O H H i-Pr OH OH OH H2O2, NaHCO3 MeOH alkenes 59% overall yield 77:23 (syn,syn triol: rest) Leighton JACS 2000 (122) 8587. i-Pr O Si H O Rh(I) O CO CO 1 mol% 1000 psi CO, benzene, 60oC i-Pr O Si O H i-Pr O Si O i-Pr OAc OAc 1. TBAF 2. Ac2O alkynes 70% overall yield 23:1 (1,5-anti: 1,5-syn) Leighton ACIEE 2001 (40) 2915. Leighton JACS 2001 (123) 341. Schreiber JACS 1993 (115) 3360. O OTIPS Si H O Rh(I) O CO CO H2O2, NaHCO3 MeOH OH OH OH OTIPS OPMB O O O O O O O O OH 1 mol% 1000 psi CO, benzene, 60o 1. C 2. 55% overall yield Formal synthesis of Mycoticin A Schreiber intermediate to Mycoticin A
M C. White, Chem 153 Hydrocarbonylation-215- Week of octo ber 29. 2002 Hydroesterification High pressure condi PPh3 CO,Me CO (300 atm), MeOH Me only source of hydro 4: 6 dr( hydroesterification Consiglio Garr. Chim. Ital. 1975(105)1133 Proposed carboxylate insertion mechanism CO,Me PPh Pd HCI Ph3p PPh PhaP H Insertion of the ester PPh2 occurs at the least sterically hindered OMe OMe olefinic carbon Stille Comprehensive Organic Synthesis 1993 PPh Volume 4; Chapter 4.5
M.C. White, Chem 153 Hydrocarbonylation -215- Week of October 29, 2002 Hydroesterification CO (300 atm), MeOH 100oC Me Me Et Ph3P Pd(II) Cl PPh3 Cl catalytic Me Me H CO2Me Et only source of hydrogen is protic solvent 94:6 dr ( hydroesterification is predominantly cis) High pressure conditions: Consiglio Gazz. Chim. Ital. 1975 (105) 1133. Ph3P Pd(II) Cl PPh3 Cl Ph3P Pd(II) Cl PPh3 O Cl Ph3P Pd(II) Cl PPh3 O OMe HCl Pd(II) Cl PPh3 O OMe R' Pd(II) Ph3P Cl R' CO2Me PPh3 MeOH PPh3 HCl R CO2Me Proposed carboxylate insertion mechanism: Stille Comprehensive Organic Synthesis 1993; Volume 4; Chapter 4.5 Insertion of the ester occurs at the least sterically hindered olefinic carbon
M.C. White, Chem 153 Hydrocarbonylation-216- Week of october 29. 2002 Hydroamination NHR CO(150-400am),H2N The clear limitation of these systems 150-200°C Is the extreme temperatures and pressures that are necessary to effect the hydrocarbon lative pro ditions to obtain the methyl ester (OC)3C(Co( CO)3=(OC)4 Co-Co(CO)4 HNR Hemiacetal intermedaite (OC) Co-H O NHR in the reaction of an analogous manganese Stille Comprehensive Organic Synthesis 1993 (O0)4C0 (OC)Co Volume 4; Chapter 4.5
M.C. White, Chem 153 Hydrocarbonylation -216- Week of October 29, 2002 CO (150-400 atm), H2NR' 150-200oC catalytic only source of hydrogen is H2NR' Natta JACS. 1952 (74) 4496. High pressure and high temperature conditions: Co2(CO)8 O NHR' + O NHR' MeOH can also be used under these conditions to obtain the methyl ester Hydroamidation The clear limitation of these systems is the extreme temperatures and pressures that are necessary to effect the hydrocarbonylative process Proposed hydride mechanism: Stille Comprehensive Organic Synthesis 1993; Volume 4; Chapter 4.5 Independently prepared Co-H has been shown to effect both hydroamidation and hydroesterification processes. Hemiacetal intermedaite is speculative and based on the reaction of an analogous manganese complex with alcohols. (OC)3Co Co(CO)3 C C O O (OC)4Co Co(CO)4 H2NR' ? (OC)4Co H (OC)3Co H R R CO (OC)3Co R (OC)4Co R CO (OC)4Co R O H2RN (OC)4Co R O NHR H R O NHR