Diastereocontrol in Bicyclic Synthesis

Question 1

Control in bicyclic systems

Answer 1

cis fused rings have good control, have convex and concave face, upper convex face is less sterically hindered

Question 2

bicyclic epoxidation

Answer 2

reagent choice determines diastereoselectivity
all relative to H and bicyclic ring
mCPBA gives cis
NBS with H2O then NaOH gives trans product, goes via cis bromonium ion, water attacks via Sn2 giving Br and OH anti then OH- deprotonates OH and intramolecular attack on Br gives anti product

Question 3

thermodynamic control

Answer 3

selectivity dependent on energy of product, typically long reactions at high T

Question 4

kinetic control

Answer 4

selectivity dependent on energy of TS, low temp reaction