>>10950664Seconding carey&sundberg, also adding zweifel's modern organic. Greene's protecting groups, and Yamamoto's lewis acids are also good references.
Baran's group puts out a lot of slides for niche topics; hypervalent iodine, C-H directing groups, his heterocycle series is a god send.
If you prefer to learn by example, try looking up medchem patents,
>https://www.organic-reaction.com/patent-highlights/sanofi-aventis/to see what kind of crazy shit can be done with heterocycles and condensations. SynArchive,
>https://www.synarchive.com/also has a ton of more academic examples, heavier on the C-C linkages and protecting groups
Two interesting articles:
doi.org/10.1021/ja9915201doi.org/10.1080/00397911.2011.591956 
