Acid chloride, alcohols from reaction with Grignard reagents

Ketones can also be prepared from acid chlorides by reaction at low temperature with an excess of acid chloride. Tetrahydrofuran is the preferred solvent." The reaction conditions must be controlled to prevent formation of tertiary alcohol by addition of Grignard reagent to the ketone as it is formed. 

The ketone 15 was eventually prepared by Grignard addition to Weinreb amide 21, as shown in Scheme 5.5. The Weinreb amide 21 was prepared from p-iodobenzoic acid (20). The phenol of readily available 3-hydroxybenzaldehyde (22) was first protected with a benzyl group, then the aldehyde was converted to chloride 24 via alcohol 23 under standard conditions. Preparation of the Grignard reagent 25 from chloride 24 was initially problematic. A large proportion of the homo-coupling side product 26 was observed in THF. The use of a 3 1 mixture of toluene THF as the reaction solvent suppressed this side reaction [7]. The iodoketone 15 was isolated as a crystalline solid and this sequence was scaled up to pilot plant scale to make around 50 kg of 15. 

Dibenzocycloheptenone (24-6) also serves as a starting material for the preparation of one of the few medicinal products that contains an acetylenic linkage. Reaction of (24-6) with the Grignard reagent from propargyl bromide leads to the alcohol (27-1). The free proton acetylene is sufficiently acidic for that center to take part in a Mannich reaction. Thus, reaction of (27-1) with formaldehyde and dimethylamine gives the adduct (27-2). Dehydration by means of thionyl chloride completes the synthesis of intriptyline (27-3) [28]. 

Acetic formic anhydride has been prepared by the reaction of formic acid with acetic anhydride2 3 and ketene,4,5 and of acetyl chloride with sodium formate.6 The present procedure is essentially that of Muramatsu.6 It is simpler than others previously described and gives better yields. It is easily adapted to the preparation of large quantities, usually with an increase in yield. Acetic formic anhydride is a useful intermediate for the formyl-ation of amines,3,7 amino acids,8,9 and alcohols,2,10 for the synthesis of aldehydes from Grignard reagents,11 and for the preparation of formyl fluoride.12... 

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