Propanediol aldehydes

The catalyst is a cobalt carbonyl that is prepared in situ from cobaltous hydroxide, and nonylpyridine is the promotor. Oxidation of the aldehyde produces 3-hydroxypropionic acid. 1,3-Propanediol and 3-hydroxypropi-onic acid could also be produced from acrolein (Chaper 8). ... 

Porco s route to (—)-kinamycin C (3) began with 2,5-dihydroxybenzaldehyde (38), which was elaborated to the enone 35 by the sequence shown in Scheme 3.6. Regioselective bromination [25] followed by methylation and reduction of the aldehyde function afforded the primary alcohol 39. The alcohol 39 was dearomatized by treatment with bis(acetoxy)iodobenzene, to afford the quinone monoketal 41. Transketalization with 1,3-propanediol followed by silylation of the primary alcohol generated the silyl ether 42 in 72 % yield over three steps. 

The key step in the synthesis of A-ring fragment 50 [56] is the chelation-controlled addition of allylstannane 53 to aldehyde 52, which sets the C7 stereocenter and introduces the C8 gem-dimethyl moiety. Aldehyde 52 is itself prepared from 1,3-propanediol using the author s protocol for titanium-catalyzed enantioselective allylstannation [57], which sets the C5 stereocenter, followed by chelation-controlled Mukaiyama aldol addition [58] to establish the C3 stereocenter (Scheme 5.6). 

Several methods and reaction pathways have been reported for the conversion of glycerol in the literature, such as etherification, esterification [1], and oxidation [2], Via ionic dehydration acetol [3] and acrolein can be produced. The radical steps result in aldehydes, allyl alcohol, etc. [4], If the dehydration is followed by a hydrogenation step, propanediols (1,2- or 1,3-) can be obtained [5-6]. 

Similarly, horse liver dehydrogenase oxidized 3-fluoro-1,2-propanediol 74 to the aldehyde which further transformed into fluorolactic acid 75 with optically pure form by yeast aldehyde dehydrogenase [67,68]. 

Propanediol is first protected at one end as a TBS ether The free alcohol function is then subjected to a Swern oxidation, leading to aldehyde 22. 

The ratio of 33A and 33B proved to be slightly solvent-dependent (Table V). The reactions of 3-amino-l,2-propanediol with substituted aromatic aldehydes in CDC13 resulted in five-component ring-chain tautomeric equilibria. Besides the open-chain form 34A, two epimeric oxazolidines (34B and 34B ) and two epimeric tetrahydro-l,3-oxazines (34C and 34C ) were identified in the tautomeric mixture. The proportions of the tautomers in the equilibrium for X = p-NC)2 were [34A] [34B] [34B ] [34C] [34C ] = 40.7 7.0 5.9 9.7 36.7 (94MI1, 94MI2). 

Aldehydes and ketones are usually protected by converting them to acetals by reaction with an alcohol in the presence of acid (see Section 18.9). Although many different alcohols could be used, ethylene glycol (1,2-ethanediol) or 1,3-propanediol is most often... 

A new synthetic approach to polycyclic aromatic compounds has been developed based on double Suzuki coupling of polycyclic aromatic hydrocarbon bis(boronic acid) derivatives with o-bromoaryl aldehydes to furnish aryl dialdehydes. These are then converted to larger polycyclic aromatic ring systems by either (a) conversion to diolefins by Wittig reaction followed by photocyclization, or (b) reductive cyclization with trifluoromethanesulfonic acid and 1,3-propanediol (Eq. (12)) [30]. 

The cyclization in Step B is an improvement of Butler s procedure for the synthesis of which employs less convenient reagents, KNH and l-bromo-3-chloroacetone acetal. Beside the acetals derived from neopentyl glycol, those derived from ethanol, 1,3-propanediol and 2,4-pentanediol have been synthesized by the present method. The second part of Step B involves the formation and the electrophilic trapping of cyclopropenyl anion 2, which is the key element of the present preparations. Step B provides a simple route to substituted cyclopropenones, but the reaction is limited to alkylation with alkyl halides. The use of lithiated and zincated cyclopropenone acetal, on the other hand, is more general and permits the reaction with a variety of electrophiles alkyl, aryl and vinyl halides, Me3SiCl, Bu3SnCl, aldehydes, ketones, and epoxides. Repetition of the lithiation/alkylation sequence provides disubstituted cyclopropenone acetals. 

Metriol (Pentaglycerol, 2-(Hydroxymethyl)-2-methyl-l, 3-propanediol, Methyltrimethylol-methane). H3G.C(CH20H)3 mw 120.15 white needles from abs ale mp 199° (sublimes without decompn). Was first prepd by Hosaeus (Ref 2) by condensing formaldehyde and propionic aldehyde in cold aq soln in the presence of lime. Metriol is v sol in w, ale and acet ac is insol in eth. It may be nitrated to an expl trinitrate, and acetylated to a nonexpl triacetate Refs 1) Beil 1, 520 2) H. Hosaeus, Ann... 

Chiral amino alcohols can be prepared by reaction of chiral epoxides with amines. Enantiopure (25, 3.R)-2,3-epoxy-3-phenylpropanol anchored to Merrifield resin has been used for ring-opening with secondary amines in the presence of lithium perchlorate to afford polymer-supported chiral amino alcohols 47 (Eq. 18) [56], By analogy, (2i ,35)-3-(cis-2,6-dimethylpiperidino)-3-phenyl-l,2-propanediol has been anchored to a 2-chlorotrityl chloride resin (48). Although this polymer had high catalytic activity in the enantioselective addition of diethylzinc to aldehydes, the selectivity of the corresponding monomeric catalyst was higher (97 % ee) in the same reaction. 

Even under optimal conditions, all tested catalysts produced only trace amounts of the desired 3,3-dimethyl-oxetane (0 1 %). The two aldehydes 2-methyl-propanal (I), formed via a cleavage reaction and 2-methyl-butanal (II) (rearrangement) were found to be the major products (Fig.l). Other byproducts were dimers of 2,2-dimethyl-propanediol, acetals of the starting material with (I) and (II) as well as the corresponding alcohols and olefins. A typical product distribution for a NaY- zeolite is given in Table 1. Since especially the formation of the cleavage products was unexpected, we decided to investigate the reaction in more detail. 

Acetals from a,/3-unsaturated aldehydes and optically active 1-aryl-1,3-propanediols are cyclopropanated by the diiodomethane/diethylzinc reagent with moderate selectivity69. After oxidative cleavage of the auxiliary, cyclopropanecarboxylic acids are obtained with 21 -78% ee. Thus, the C2-symmetric auxiliaries seem to be superior for this kind of [2 + 1] cycloaddition. 

Acetalization. The use of NBS as a catalyst for acetalization with triethyl orthoformate shows chemoselectivity in favor of aldehydes, although formation of ketone acetals is also feasible. 1,3-Dioxanes are formed when 1,3-propanediol is present in the reaction. ... 

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