EAA Group Problems – 21st April 2015 Question 1. Please provide a structure for A with relative stereochemical detail, and a mechanism for its formation.

Question 2. Suggest the identities of structural isomers B and C with mechanistic rationale for their formation.

Question 3. Give mechanisms for all steps, and suggest reagents and stereochemistry where indicated.

 

A

C46H38N2O6

PhPh

HO

O O

[Ru] (2 mol%)TFA (5 mol%)

toluene100 °C, 1 h

then N-phenylmaleinimide (2 eq.)100 °C, 5 h

NN

OPh

Ph

Ru(CO)3

[Ru]

C

C19H22O

C

XOPh

CH2Cl2rt

X = SiR3

(IPr)AuCl (5 mol%)Na[Me3NB12Cl11] (5 mol%)

i-PrOH (1.1 eq.)

B

C19H22OCH2Cl2

rtX = H

(IPr)AuCl (5 mol%)Na[Me3NB12Cl11] (5 mol%)

i-PrOH (1.1 eq.)

OSi

CO2Et

Et2AlCl

PhMe0 °C

9:1 dr

Synthesis? Stereochemistry?

OSi

I

ii. I2, PPh3imidazole

i. LiAlH4Et2O

D

Reagents?

OSi

OH

iii. DMP, NaHCO3iv. SmI2, THF, MeOH

i. m-CPBA, NaHCO3ii. PPTS

E

MANY Steps

O

MOMO

PhthNO

CHO

O

MOMO

PhthN CO2Me

i. Bn2NH2⋅O2CCF3PhMe, 50 °C

ii. AcOH, NaCN, MeOHthen MnO2

DCE

H2 (900 psi)[(cod)(Py)(PCy)3]IrBArF4

F

iii. Ph2BBr, CH2Cl2

i. N2H4⋅H2O, EtOHii. aq. NH4Cl, EtOH

G

Stereochemistry?