NaBH4 reaction

When glucose (Problem 19.72) is treated with NaBH4, reaction occurs to yield sorbitol, a polyalcohol commonly used as a food additive. Show how this reduction occurs. 

Substrate Mol. equiv. of NaBH4 Reaction conditions Product % yield... 

Figure 7. TPP Mn(III)-catalyzed autoxidation of cyclohexene with NaBH4, Reaction 1 without NaBH4, Reaction 2...

This is a reaction that would also work in the laboratory with NaBH4 as the reducing agent, but there is a big difference. The product from the NaBH4 reaction must be racemic-—no optical activity has been put in from compound, reagent, or solvent. 

Reduction of the a,p-unsaturated carbonyl compound forms an allylic alcohol with NaBH4 (Reaction [3]), or a ketone with H2 and Pd-C (Reaction [4]) see Section 20.4C. 

Scheme XXXIII. Further routes to dl-perhydrohistrionicotoxin and its 2,7-epimeric analog (70). A i) n-PentylLi, ii) HCl. B i) LiAlH4, ii) Dihydrofuran, iii) a. Li, b. 2-n-Butylcyclohexan-1,3-diene methyl enol ether. C i)AcOH, ii)CH3S02Cl, (C2Hs)3N, iii)LiN3. D i)hv. E i) Lindlar s Pd, H2. F i) 136 . F i) Acid or base and heat. G i) Li, NH3, ii) NABH4 Reaction G undoubtedly affords both 7-butyl stereoisomers...

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