Official and secondary sources for the solutions manual include: Official Publisher Site
The difficulty of Advanced Organic Chemistry, Part A is not a bug—it is a feature. The field of physical organic chemistry is built on rigorous, nuanced thinking. A solution manual, if designed with pedagogy in mind, would not dumb down this rigor. Instead, it would illuminate the path. It would show the silent steps between question and answer, training the next generation of organic chemists to think not just correctly, but mechanistically. Official and secondary sources for the solutions manual
You can find a comprehensive overview of the topics covered in Part A on Google Books nuanced thinking. A solution manual