In lecture we discussed the nature of the nucleophile for the attack of the carbonyl.
LiAlH4 acts as a better nucleophile (hydride) than NaBH4. I know there is no hydroboration! So I would have expected that LiAlH4 gives more Felkin Anh product as the NaBH4 gives.
However LiAlH4 gives a Felkin Anh : Anti Felkin Anh ratio of 3:1 and NaBH4 gives a ratio of 5:1.
detailed reaction Source: Carreira, E.M.; Classics in Stereoselective Synthesis
Is there any good rational?