CHEM 2320-1
TEST 4
Dr. Bachrach
11-19-09

1) Provide the IUPAC name of the following compounds.

2) Using any necessary organic or inorganic reagents synthesize 3,4,5-tribromotoluene from toluene.

3) What is the purpose of the BOC group in peptide synthesis?

The BOC group is used to protect the N-terminus of an amino acid. It can be readily removed afterwards so that chain extension can be done on the N-side, or deprotected when the entire synthesis is complete.

4) Provide the product(s) of the following reactions.

a)

b)

c)

5) Somatostatin is a tetradecapeptide of the hypothalamus that inhibits the release of pituitary growth hormone. Determine the primary structure of somatostatin based on the following results:

a) Edman degradation gave PTH-Ala

b) Selective hydrolysis gave the following peptide sequences:

Phe-Trp          Thr-Ser-Cys         Lys-Thr-Phe
Thr-Phe-Thr-Ser-Cys           Asn-Phe-Phe-Trp-Lys           Ala-Gly-Cys-Lys-Asn-Phe

c) Somatastatin contains a disulfide bridge.

6) Provide the necessary reagent(s) to enable the following transformations.

a)

b)

c)

d)

e)

7) Regardless of whether one starts with α-D-mannose or β-D-mannose, upon reaction with ethanol and dilute acid, one gets the same two glycosides in the exact same ratio. Explain this result using the mechanism of the reaction.

D-mannose

The intermediate cation can be attacked by ethanol form either side, leading to the α and β glycosides. This intermediate is the same whether you start with α-mannose or β-mannose. So one will obtain the exact same ratio of α:β glycosides regardless of which sugar you begin with.