Question

Scheme 3. D-A Cyclopropane Approach to Cyclopropyl Carbinols 4a-v, 4x, and 4y LiEt 8H 1) TsN3 NEt3 CH3CN upto 98% THF Up to 90% 4a-4v 2) Rh2esp2RR THF ?? to 90% CH2Cl2 up to 92% 4x/4y OH O ??? 4b R 4-Me 4c R = 4-OMe 4e R = 4-Br 4g R 2-Br R 4h ?? ? ?? ??? OMe OMe Ai R = 2-Np aj R = 2-furyl OH O 4m 1R 3-thienyl ?? ? ??? 40 R 4-OMe 4p R H OMe 4s ?? ? ?? ? R OHO 4t 4xR-Me Instead, 4w was synthesized using Nishii's Reformatsky approach (Scheme 4).21 1,1-Dibromocyclopropane 10w Scheme 4. Reformatsky Approach to Carbinol 4w 1) n-BuLi Br B then CO2 Br>< "OMe Me Me Mel 10w 11w .46% (prepared in one step (over two steps) from styrene)

Answer 1

10.  

Scheme 3, cyclopropane is Electrofile

The borohydride transfers a hydride(H - atom with a pair of electron)to the carbonyl carbon. It acts as a nucleophile. Transfer an alkyl(alkyi group with a pair of electrons)ie a nucleophile 1. In the first step, the a - bromo ester reacts with zinc to form zinc enolate which is also called as refoematsky enolate. 2. This formed enolate reacts as the nucleophilic partner in an addition to give alpha - hydroxyl esters. 3. Hydrolysis takes place and a - hydroxyl ester is generated. Probably because Reformastky's reaction is more enatioselective. Sodium borohydride and its derivatives reduce aldehydes and ketones to alcohols, but, unlike the more aggressive reducing agent lithium aluminum hydride, it will not generally reduce esters.

Scheme 4, cyclopropane 11w is Nucleophile
The borohydride transfers a hydride(H - atom with a pair of electron)to the carbonyl carbon. It acts as a nucleophile. Transfer an alkyl(alkyi group with a pair of electrons)ie a nucleophile 1. In the first step, the a - bromo ester reacts with zinc to form zinc enolate which is also called as refoematsky enolate. 2. This formed enolate reacts as the nucleophilic partner in an addition to give alpha - hydroxyl esters. 3. Hydrolysis takes place and a - hydroxyl ester is generated. Probably because Reformastky's reaction is more enatioselective. Sodium borohydride and its derivatives reduce aldehydes and ketones to alcohols, but, unlike the more aggressive reducing agent lithium aluminum hydride, it will not generally reduce esters.


The borohydride transfers a hydride(H - atom with a pair of electron)to the carbonyl carbon. It acts as a nucleophile. Transfer an alkyl(alkyi group with a pair of electrons)ie a nucleophile 1. In the first step, the a - bromo ester reacts with zinc to form zinc enolate which is also called as refoematsky enolate. 2. This formed enolate reacts as the nucleophilic partner in an addition to give alpha - hydroxyl esters. 3. Hydrolysis takes place and a - hydroxyl ester is generated. Probably because Reformastky's reaction is more enatioselective. Sodium borohydride and its derivatives reduce aldehydes and ketones to alcohols, but, unlike the more aggressive reducing agent lithium aluminum hydride, it will not generally reduce esters.

11. Probably because Reformastky's reaction is more enatioselective.

12. Sodium borohydride and its derivatives reduce aldehydes and ketones to alcohols, but, unlike the more aggressive reducing agent lithium aluminum hydride, it will not generally reduce esters.