Domain: Organic synthesis

An organic compound, 7-nitrohept-3-yne, reacts with but-3-en-2-one in the presence of diisopropylamine (iPr2NH) and chloroform (CHCl3), followed by reaction with titanium(III) chloride (TiCl3) in water (H2O) and dimethoxyethane (DME), leading to the formation of product A. Thereafter, product A is treated with sodium hydroxide (NaOH), followed by reaction with hydrogen (H2) in the presence of Lindlar's catalyst, resulting in the formation of the final organic product.
 Predict the molecular weight of the final organic product.

Grading rubric:
criterion: Identifies Step 1 (iPr2NH and CHCl3) as a conjugate Michael addition of 7-nitrohept-3-yne to the α,β-unsaturated ketone but-3-en-2-one.
weight: 10
criterion: States compound A specifically as 5-nitroundec-8-yn-2-one formed after the Michael addition step.
weight: 10
criterion: Identifies Step 2 (TiCl3 in H2O/DME) as a Nef reaction.
weight: 10
criterion: States the Step 2 product explicitly as undec-8-yne-2,5-dione.
weight: 10
criterion: Identifies Step 3 (NaOH treatment) as an intramolecular aldol cyclization.
weight: 10
criterion: Correctly identifies compound B as 3-methyl-2-(pent-2-yn-1-yl)cyclopent-2-en-1-one.
weight: 10
criterion: Identifies Step 4 as selective catalytic hydrogenation using Lindlar’s catalyst.
weight: 10
criterion: Correctly identifies the final product skeleton C as a substituted cyclopent-2-en-1-one bearing a pent-2-en-1-yl side chain.
weight: 20
criterion: Correctly determines the molecular weight of the final organic product C as 164.25 g·mol⁻¹ (within ±0.05 g·mol⁻¹).
weight: 10

Answer:
164.25 g·mol⁻¹