Cytovaricin is a macrolide antibiotic that possesses promising antineoplastic activity. In an effort to understand which...

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Cytovaricin is a macrolide antibiotic that possesses promising antineoplastic activity. In an effort to understand which portion of the molecule is responsible for this biological activity, Prof. David Evans completed a convergent total synthesis. The following question relates to that work. он он он он OH Cytovaricin Meo OH In Prof. Evan's synthesis, the oxazolinone (A) was deprotonated to generate an enolate (B) with defined stereochemistry, which then participated in an aldol reaction with aldehyde (C) to give the product (D). i. LDA enolate (B) Ph (A) OPMB (C) ii. H"/H20 recall that LDA = OH ОРМВ Ph (D) a) Suggest a structure for enolate (B) (1mark) b) Using cyclic deprotonation models, justify why the enolate (B) has a particular stereochemistry (E or Z) (8 marks) c) Using 3D representations, invoke a Zimmerman-Traxler structure to account for why compound (D) has the syn stereochemical relationship between the stereogenic centres labelled 2 and 3. (8 marks) d) Will compound (D) be a single enantiomer, racemic, or achiral? Justify your answer using a 3D representation. (4 marks) Cytovaricin is a macrolide antibiotic that possesses promising antineoplastic activity. In an effort to understand which portion of the molecule is responsible for this biological activity, Prof. David Evans completed a convergent total synthesis. The following question relates to that work. он он он он OH Cytovaricin Meo OH In Prof. Evan's synthesis, the oxazolinone (A) was deprotonated to generate an enolate (B) with defined stereochemistry, which then participated in an aldol reaction with aldehyde (C) to give the product (D). i. LDA enolate (B) Ph (A) OPMB (C) ii. H"/H20 recall that LDA = OH ОРМВ Ph (D) a) Suggest a structure for enolate (B) (1mark) b) Using cyclic deprotonation models, justify why the enolate (B) has a particular stereochemistry (E or Z) (8 marks) c) Using 3D representations, invoke a Zimmerman-Traxler structure to account for why compound (D) has the syn stereochemical relationship between the stereogenic centres labelled 2 and 3. (8 marks) d) Will compound (D) be a single enantiomer, racemic, or achiral? Justify your answer using a 3D representation. (4 marks)