Question

The fluorenylmethoxycarbonyl group is used to protect the amino group of amino acids during the Merrifield solid phase peptide synthesis procedure. The group is then removed by treatment with piperidine. The mechanism of addition and removal is as follows: 1. The amino acid under basic conditions reacts with Fmoc chloride followed by deprotonation to give tetrahedral intermediate 1; 2. collapse of the tetrahedral intermediate gives the Fmoc-aa; 3. in the removal sequence, deprotonation of the tertiary carbon gives carbanion 1; 4. elimination gives 9-methylene fluorene and carbamate 2; 5. decarboxylation gives CO2 and the amino acid. FMOC chloride Work out the above mechanism on a separate sheet of paper and then draw the structure of carbanion 1. • You do not have to consider stereochemistry. • Use R1 to represent a generic R group for the amino acid. The R group tool is located in the charges and lone pairs drop-down menu.

          The fluorenylmethoxycarbonyl group is used to protect the amino group of amino acids during the Merrifield solid phase peptide synthesis procedure. The group is then removed by treatment with piperidine. The mechanism of addition and removal is as follows:

1. The amino acid under basic conditions reacts with Fmoc chloride followed by deprotonation to give tetrahedral intermediate 1;
2. collapse of the tetrahedral intermediate gives the Fmoc-aa;
3. in the removal sequence, deprotonation of the tertiary carbon gives carbanion 1;
4. elimination gives 9-methylene fluorene and carbamate 2;
5. decarboxylation gives CO2 and the amino acid.

FMOC chloride

Work out the above mechanism on a separate sheet of paper and then draw the structure of carbanion 1.

• You do not have to consider stereochemistry.
• Use R1 to represent a generic R group for the amino acid. The R group tool is located in the charges and lone pairs drop-down menu.

The fluorenylmethoxycarbonyl group is used to protect the amino group of amino acids during the Merrifield solid phase peptide synthesis procedure. The group is then removed by treatment with piperidine. The mechanism of addition and removal is as follows:

1. The amino acid under basic conditions reacts with Fmoc chloride followed by deprotonation to give tetrahedral intermediate 1;
2. collapse of the tetrahedral intermediate gives the Fmoc-aa;
3. in the removal sequence, deprotonation of the tertiary carbon gives carbanion 1;
4. elimination gives 9-methylene fluorene and carbamate 2;
5. decarboxylation gives CO2 and the amino acid.

FMOC chloride

Work out the above mechanism on a separate sheet of paper and then draw the structure of carbanion 1.

• You do not have to consider stereochemistry.
• Use R1 to represent a generic R group for the amino acid. The R group tool is located in the charges and lone pairs drop-down menu.

Added by Daniel B.

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