1.3- Propanediol reactions with carbonyls

Methylene-l,4-alkanediols. The PdCl2-(PhCN)2 - SnCl couple transforms an allylic alcohol into an allyl anion equivalent. 2-Methylene-1,3-propanediol can be used to prepare 2-methylene-1,4-alkanediols on reaction with carbonyl compounds. 

Reactions with Carbonyls. The chemistry of 1,3-propanediol (1) is dominated by acetal formation." Its ketone acetals show differential hydrolytic stability cyclopentanone acetals hydrolyze faster than cyclohexanone acetals, and both hydrolyze faster than ethylene glycol-derived acetals (Table 1). The ketone-acetal equilibrium lies far to the left. Its aldehyde... 

Dioxepan-2-ones (103) have been manufactured from diols, paraformaldehyde, and carbon monoxide in the presence of a copper(I) or silver carbonyl catalyst (Scheme 10). Thus, treatment of CU2O with 98% H2SO4 and CO and reaction with paraformaldehyde and 1,2-propanediol under CO atmosphere gave 5-methyl-l,4-dioxepan-2-one in high yield <89JAP0i09358i>. By the same protocol, l,4-dioxepan-2-one could be obtained by cyclocondensation of trioxane with CO and... 

Reaction of dihydroxyacetone with ammonia and hydrogen is a good illustration of the different reactivities of hydroxyl and carbonyl groups during amination over metal catalysts. When the reaction is performed at a relatively mild temperature (< 100 °C, 100 bar) in liquid ammonia, Raney Ni affords 2-amino-1,3-propanediol in 99 % yield [28]. Under these conditions activation of hydroxyl groups is negligible. Similarly, the carbonyl group of an aldose or ketose reacts with ammo-... 

A variation in ketal protection introduces alkyl substituents on the diol moiety. Money, for example, used 2,2-dimethyl-1,3-propanediol to protect the ketone in 116 (forming 117). Use of this protecting group allowed the reaction of the allylic unit in 117 with butyllithium and also conversion of the resulting alcohol product to chloride 118. Deprotection of the carbonyl gave 119 in a synthesis of camphorenone.98... 

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