Mitsunobu reaction bromides

Sulfonamides of primary amines are readily deprotonated (pAia 9-11) and can thus be N-alkylated or N-arylated. Because of their high nucleophilicity and low basicity, deprotonated sulfonamides also react smoothly with less reactive electrophiles, such as n-alkyl bromides [136] (Table 8.9). Sulfonamides can also be N-alkylated with aliphatic alcohols under Mitsunobu conditions. Suitable solvents for the N-alkylation of sulfonamides on polystyrene by Mitsunobu reaction are DCM, toluene, and THF. 

Hydroxypyridines are readily alkylated under a variety of conditions. Mitsunobu reaction with alcohols occurs selectively at oxygen in the presence of PPh3 and DEAD in THF at room temperature <2003TL725>. The 3-hydroxy group may be selectively alkylated in the presence of aliphatic hydroxyl groups. Pyridine 104 is alkylated at the aromatic position with dodecyl bromide in the presence of potassium carbonate in DMF at 95 °C <20030BC644> (Equation 70). 

The Mitsunobu reaction was discussed in Chapter 17, p. 000. Mitsunobu chemistry involves using a phosphorus atom to remove the OH group, after the style of PBrs as a reagent to make alkyl bromides from alcohols. 

In 1992, Parker and Fokas reported the short step (11 steps) synthesis of racemic dihydroisocodeine, which completes a formal synthesis of codeine and morphine [58]. The key feature of their synthesis are (1) a construction of an aryl ether moiety (connection of the A and C rings) by Mitsunobu reaction, (2) a tandem radical cyclization of aryl bromide possessing the C-ring precursor to generate the A-B-C-E ring of morphine, and (3) a hydroamination for the construction of the D-ring by the reaction of a tosylamide with Li/NH3. In 2006, they reported the chiral version of the synthesis of dihydrocodeinone [59]. 

The PSB ether can be prepared from the alcohol using the Mitsunobu reaction, from the bromide with base (K2CO3, TBAI, CS2CO3 or NaH, DMF) or from the bromide... 

Figure 6.32 Successes and failure of carbonate protection in an attempt to make aryl P-mannobiosides. The formation of the cyclic orthocarbonate must be entirely due to the complex phosphine oxide leaving group in the Mitsunobu reaction, since 4,6-di-O-acetyl-a-D-mannopyranosyl bromide 2,3-carbonate gave the expected aryl P-mannosides on reaction -with phenoxides. ...

A number of acyclic <7-dialkoxyphosphoranes (18) have been prepared in moderate to high yields by the reaction of bromotriphenylphosphonium bromide (17) with the relevant sodium alkoxide in alcohol and ethereal solvents. The method offers obvious advantages over the peroxide route and in some cases (R=Pr ) higher yields than the Mitsunobu reaction but at the... 

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