The major products A and B formed in the following transformations are

Concept:

• According to HSAB principle, both thermodynamically and kinetically hard acids prefer hard bases and soft acids soft bases. Specifically, thermodynamically, hard acids form stronger acid-base complexes with hard bases while soft acids form stronger complexes with soft bases.
• For a \(\alpha,\beta\)-unsaturated carbonyl compound, the \(\alpha\)-c atom act as a soft electrophile, and the \(\beta\)-c atom act as a hard electrophile.

Explanation:

• The reaction pathway is shown below:

• From the above reaction, we can see that in presence of NaH (strong base), the amine group (-NH₂ group) undergoes deprotonation and forms a hard nucleophilic center (N atom). Thus, it will attack the hard electrophile according to the SHAB principle and forms the major product A.
• In presence of NaH (strong base), the thiol group (-SH group) undergoes deprotonation and the S atom being a soft nucleophilic center will attack the softer electrophile according to the SHAB principle. This reaction leads to the formation of compound B as the major product.

​Conclusion:

The major products A and B formed in the following transformations are