you can refer to the following list of books for organic chemistry for AIIMS-

• Modern ABC of Chemistry for Class 11th & 12th (Vol. 1 & 2)
• Physical Chemistry by O P Tandon
• Arihant Organic Chemistry
• Dinesh Chemistry
• Concise Inorganic Chemistry by J.D. Lee for Inorganic Chemistry
• Objective NCERT at your fingertips Chemistry by MTG-

I have also included NCERT as a good book for organic chemistry as AIIMS syllabus also covers a portion of class 11th and 12th chemistry. To start with your preparation and good understanding of concepts it is good to start with NCERT and also refer to the above books for good preparation.

All the best!