tert-butyl (2R)-2-bromo-4-methylpentanoate

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: Into dichloromethane (80 mL) was condensed isobutene to double the volume (at -50° C. CHCl3 /dry ice). To this solution was added (2R)-2-bromo-4-methylpentanoic acid (28 g, 143.6 mmol) and maintaining the temperature between -40° and -50° C. concentrated sulphuric acid (1 mL) was added dropwise. The reaction was then allowed to warm to room temperature over 20 hours. The solution was then concentrated before adding additional methylene chloride (300 mL) which was subsequently washed with saturated NaHCO3 (2×100 mL) followed by water (2×100 mL). After drying over Na2SO4, the organic layer was filtered and concentrated to give a yellow oil. The material was distilled to give 23 g of (2R)-2-bromo-4-methylpentanoic acid t-butyl ester as a clear colorless oil. was added dropwise The solution was then concentrated before adding additional methylene chloride (300 mL) which was subsequently washed with saturated NaHCO3 (2×100 mL) After drying over Na2SO4 the organic layer was filtered concentrated to give a yellow oil The material was distilled

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: Into dichloromethane (80 mL) was condensed isobutene to double the volume (at -50° C. CHCl3 /dry ice). To this solution was added (2R)-2-bromo-4-methylpentanoic acid (28 g, 143.6 mmol) and maintaining the temperature between -400 and -50° C. concentrated sulphuric acid (1 mL) was added dropwise. The reaction was then allowed to warm to room temperature over 20 hours. The solution was then concentrated before adding additional methylene chloride (300 mL) which was subsequently washed with saturated NaHCO3 (2×100 mL) followed by water (2×100 mL). After drying over Na2SO4, the organic layer was filtered and concentrated to give a yellow oil. The material was distilled to give 23 g of (2R)-2-bromo-4-methylpentanoic acid t-butyl ester as a clear colorless oil. was added dropwise The solution was then concentrated before adding additional methylene chloride (300 mL) which was subsequently washed with saturated NaHCO3 (2×100 mL) After drying over Na2SO4 the organic layer was filtered concentrated to give a yellow oil The material was distilled

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: 33 g of 2(R)-bromo-4-methylpentanoic acid (prepared from D-leucine) was dissolved in 100 ml of methylene chloride. To this solution, at -40° C. was introduced 47 g of 2-methylpropene while stirring, and after the addition of 0.8 ml of sulfuric acid the mixture was stirred overnight at room temperature. The reaction mixture was concentrated to 1/2 in vacuo and washed with 10% sodium carbonate aqueous solution and dried over anhydrous magnesium sulfate. The solution was then evaporated in vacuo, yielding 37.4 g of 2(R)-bromo-4-methylpentanoic acid t-butyl ester. was stirred overnight at room temperature The reaction mixture was concentrated to 1/2 in vacuo washed with 10% sodium carbonate aqueous solution dried over anhydrous magnesium sulfate The solution was then evaporated in vacuo

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: Into dichloromethane (80 mL) was condensed isobutene to double the volume (at -50° C. CHCl3 /dry ice). To this solution was added (2R)-2-bromo-4-methylpentanoic acid (28 g, 143.6 mmol) and maintaining the temperature between -40° and -50° C. concentrated sulphuric acid (1 mL) was added dropwise. The reaction was then allowed to warm to room temperature over 20 hours. The solution was then concentrated before adding additional methylene chloride (300 mL) which was subsequently washed with saturated NaHCO3 (2×100 mL) followed by water (2×100 mL). After drying over Na2SO4, the organic layer was filtered and concentrated to give a yellow oil. The material was distilled to give 23 g of (2R)-2-bromo-4-methylpentanoic acid t-butyl ester as a clear colorless oil. was added dropwise The solution was then concentrated before adding additional methylene chloride (300 mL) which was subsequently washed with saturated NaHCO3 (2×100 mL) After drying over Na2SO4 the organic layer was filtered concentrated to give a yellow oil The material was distilled

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: Into dichloromethane (80 mL) was condensed isobutene to double the volume (at -50° C. CHCl3 /dry ice). To this solution was added (2R)-2-bromo-4-methylpentanoic acid (28 g, 143.6 mmol) and maintaining the temperature between -400 and -50° C. concentrated sulphuric acid (1 mL) was added dropwise. The reaction was then allowed to warm to room temperature over 20 hours. The solution was then concentrated before adding additional methylene chloride (300 mL) which was subsequently washed with saturated NaHCO3 (2×100 mL) followed by water (2×100 mL). After drying over Na2SO4, the organic layer was filtered and concentrated to give a yellow oil. The material was distilled to give 23 g of (2R)-2-bromo-4-methylpentanoic acid t-butyl ester as a clear colorless oil. was added dropwise The solution was then concentrated before adding additional methylene chloride (300 mL) which was subsequently washed with saturated NaHCO3 (2×100 mL) After drying over Na2SO4 the organic layer was filtered concentrated to give a yellow oil The material was distilled

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: 33 g of 2(R)-bromo-4-methylpentanoic acid (prepared from D-leucine) was dissolved in 100 ml of methylene chloride. To this solution, at -40° C. was introduced 47 g of 2-methylpropene while stirring, and after the addition of 0.8 ml of sulfuric acid the mixture was stirred overnight at room temperature. The reaction mixture was concentrated to 1/2 in vacuo and washed with 10% sodium carbonate aqueous solution and dried over anhydrous magnesium sulfate. The solution was then evaporated in vacuo, yielding 37.4 g of 2(R)-bromo-4-methylpentanoic acid t-butyl ester. was stirred overnight at room temperature The reaction mixture was concentrated to 1/2 in vacuo washed with 10% sodium carbonate aqueous solution dried over anhydrous magnesium sulfate The solution was then evaporated in vacuo