In Prof. Tokuyama’s synthesis, the oxazolinone (A) was deprotonated to generate an enolate (B) with defined stereochemistry, which then participated in an aldol reaction with the chiral aldehyde (C) to give the product (D).

(a) Suggest a structure for enolate (B) (2 marks) 

(b) Using cyclic deprotonation models, justify why the enolate (B) has a particular stereochemistry (E or Z). (8 marks) 

(c) Using Newman projects, account for why compound (D) has the syn stereochemical relationship between the stereogenic centres labelled 3 and 4. (8 marks) 

(d) When the auxiliary is cleaved, will the product compound (E) be a single enantiomer, racemic, or achiral? Justify your answer. (4 marks)

i. LDA N' enolate (B) (A) ii. Li 4 recall that LDA = H3 (C) iii. H*/H20 OH OH NaOMe MeO 1 4 3 (E) (D)