HCID 14154011, compound → HCID 14533810, compound

Participants

Reaction Steps

A solution of 3-bromo-1-ethyl-2-oxocyclohex-3-eneacetic acid methyl ester (10 g, 36.3 mmol, as prepared in Example 1) and copper (I) bromide-dimethyl sulfide complex (3.63 mmol, 746 mg) in 107 mL of dry tetrahydrofuran was stirred at 0° C. under nitrogen and treated with anhydrous zinc bromide (36.6 mmol, 8.17 g). After 5 minutes, the mixture was treated dropwise with 36.6 mmol of benzylmagnesium chloride (18.2 mL of 2M in THF). After 45 minutes, another 8 mmol of benzylmagnesium chloride were added followed by 350 mg of copper (I) bromide-dimethyl sulfide complex and then another 16 mmol of benzylmagnesium chloride. The reaction was quenched with 150 mL of 1M HCl and extracted with 4×50 ML of ether. The extracts were combined, dried over magnesium sulfate, and concentrated affording 3-bromo-1-ethyl-2-oxo-4-(phenylmethyl)cyclohexaneacetic acid methyl ester. This was then stirred in a solution of 74 mL of N,N-dimethylformamide and 35 mL of water and treated with 109 mmol (18.96 g) of sodium dithionite. The mixture was heated at 55° C. under nitrogen for 20 minutes, poured into 200 mL of water and extracted with 4×100 mL of 1:1 ether-petroleum ether. The extracts were combined, washed with 100 mL of water and 100 mL of saturated sodium bicarbonate (aq), dired over magnesium sulfate, and concentrated affording 10.48 g (36.6 mmol, 100% crude yield) of product as a pale yellow oil. Analysis by capillary GC demonstrated a 4.41:1 ratio of diastereomers, with the cis isomer predominating. The reduction of the intermediate 3-bromo-1-ethyl- 2-oxo-4-(phenylmethyl)cyclohexaneacetic acid methyl ester to the title compound can also be carried out as described in Example 3.

Provenance & Evidence