{"knowledge_schema": {"broad_category": "Chemistry \u2192 Organic Chemistry \u2192 Reaction Mechanisms", "refinement": "This problem involves identifying the correct starting compounds based on the products formed from specific reducing agents in chemical reactions.", "specific_scope": "The focus is on two reactions involving different reducing agents (LiBH4 and BH3) and their respective stereochemical outcomes in the synthesis of a specific compound.", "goal": "Determine the correct initial compound that leads to the specified products when reacted with the given reducing agents."}, "summary": "This problem is rooted in organic chemistry, specifically in understanding reaction mechanisms and stereochemistry. It presents a scenario where two different reducing agents are used with unidentified compounds, leading to specific stereoisomeric products. The task is to identify the correct initial compound that, when reacted with the respective reducing agents, yields the specified products. The answer indicates that the correct initial compound for both reactions is (S)-3-ethyl-5-isobutoxy-5-oxopentanoic acid."}