Question

The following is an example of an O-linked oligosaccharide chain in oligosaccharide is linked to the protein by the side-chain functional B the side-chain functional group of serine or threonine residues. Fuda2-12) Gal(β1-34)GlcNAc(B1-4) aride chain in glycoproteins. The O-linkage means the GlcNAc(a1 )-) Serine GalNAc(al>3) al(B1- 4)GIcNAc(B13) Gal(B1->4)GIcNAc(3)G1>3) Fuc(a22) Draw out this polymer from the following Fischer projections of the monosaccharide. 1) Show each monosaccharide in the Haworth projection and in the Chair conformation for the six-member rings. 2) Show the Acetal chemical reaction mechanism of how the monosaccharides link together to make oligosaccharides and polysaccharides. Use three units: Fuct->2)Gal(B1-4)GIcNAc(B1->4) to show the mechanism 3) DRAW THE O-Linked oligosaccharide chain using chair conformations. CH OH GalNAc CH OH Gal Fuc D-Fructose D-Galactose (D) N-acetylgalactosamine GleNAc (D) N-acetylglucosamine L- serine residue in protein Instructions: Given are structures that you are to propose a route of synthesis. When usine one ofth following mechanisms to carry out a step, show the full mechanism: Sa1, Su2, E1, E2, radical, EAS, NA, NACS, carbonyl alpha substitution and carbonyl condensation reactions. You do not need the mechaism for oxidation and reduction reactions Keep in mind ste reochemistry (cis, trans, (E), (Z), (R), and (S). ite equations and mechanisms in the synthesis of the following compounds. A. Start with butanal (hint: Aldol but not condensation) and utilize any other reagents needed. 1. Wr 2-ethyl-3-oxohexanoic acid Start with 3-pentanone (hint: Wittig) and utilize any other reagents needed. B. i. 2-Ethylbut-1-ene ii. 2-Ethyl-1-bromobutane ii. 3-Methylpentan-3-ol iv. 3-Ethylpent-2-ene The following reaction involves an intramolecuiar Michael reaction followed by an intramolecular reaction. 2. Write both steps, and show their mechanism. NaOH HO ethanol

Answer 1

1) A) O CrO3, H2SO4 H3c H3c он H3C H3C butanal yH NaOEt EtOH H3C но 2-ethyM-3OXohexanoic acid H3c Nat:OEt butanal Aldol reaction O-PPh3 Wittig reaction H3C 3-methylidenepentane H3C H3C CH2-PPh3 Wittig reaction will convert ketone to alkene CH HBr/H202heat CH H2C 3-methylidenepentane Using above alkene and addition of HBr with peroxide gives product as per anti CH 3-(bromomethy)pentane markovnikov's rule

H+ CH CH H2SO4/H20 CH2 H2C H2C он CH H2C CH 3-methylidenepentane 3-methlpentan-3-ol HOH )CH3-CH-P2h3 CH H2C CH H2C H3C H3C 3-ethylpent-2-ene Wittig reaction

CH CH H2C Na+:ÖH Inter molecular Michael addition: the enolate attacks as a nucleophile to p-carbon :O CH CH3 но CH Intermolecular aldol reaction

Due to time constraints, I am unable to solve the rest of the questions.