Oxygen-to-Carbon migration

Figure 6.16 Oxygen-to-carbon migration of phosphorus in an aromatic system.

In 2008, Stoltz et al. reported the first synthesis of elatol 217 (Scheme 1.38) [47]. Starting from dimedone, the mixed carbonate 218 was prepared. Decarboxylative oxygen-to-carbon migration was effected using a Pd(0) complex based on the chiral... 

In the well-known Brook rearrangment, silyl groups migrate from oxygen to carbon, but the following example is less obvious and not necessarily predictable ... 

E. Nitrogen-to-Carbon, Oxygen-to Carbon, and SulfuMo-Carbon Migration... 

Photolysis of the methylidyne cluster HRu3(CO)] (/1, 71"COCH3) (A) (14) in cyclohexane solution leads to an unprecedented oxygen-to-carbon alkyl migration to form the bridging acyl complex HRu3(CO)10( i-> 2-C(O)CH3) (B) ... 

The isolation of the sily lacetal ketene is required when the reaction is catalyzed by a chiral Lewis acid. However, due to its instability, isolation yields of the compounds are very low. Reaction of difluoroketene silylacetal with electrophiles affords adducts with excellent ee (Figure 2.28). ° The instability of these difluoroketene silylacetals is due to the facile migration of the silyl group from oxygen to carbon, affording... 

A number of 2,3-fused chromones have been prepared from ethyl chloroformate and acetylsalicylic acid, a source of the mixed anhydride of formic and salicylic acids, and piperidinocycloalkenes (69JCS(C)935). A plausible mechanism is outlined in Scheme 165. It has not proved possible to isolate the chromanone (460) but the formation of 3-acetyl-2-methylchromone from 2-pyrrolidinopropene lends support to the intermediacy of the chromanone. The migration of the acyl group from oxygen to carbon is supported by the synthesis of 3-benzoyl-2-methylchromone rather than 3-acetylflavone from benzoylsalicylic acid and the pyrrolidinopropene. 

A theoretical study of the thermal isomerization and decomposition of oxalic acid has attempted to account for the predominant formation of C02 and HCOOH from the vapour at 400-430 K.41 Transition-state theory calculations indicate that a bimolecular hydrogen migration from oxygen to carbon of intermediate dihydroxycarbene (formed along with C02) achieved through a hydrogen exchange with a second oxalic acid... 

Metalation of phenyl tetrazolyl ethers 377 (Scheme 124), either direct or by bromine-metal exchange, triggered the heterocycle migration from oxygen to carbon [158]. Products were obtained in excellent yields for all examined derivatives (84-93%). Again, a spirocyclic four-membered ring intermediate was involved. Similarly, naphthyl derivative 380 smoothly rearranged to 381. 

A variety of bis(2-hydroxyaryI)phenylphosphine oxides (15) have been prepared from diaryl phenylphosphonates (14) by based-induced double 1,3-migration of phosphorus from oxygen to carbon. ... 

Griffin, C.E., and Mitchell, T.D., Phosphonic acids and esters. Part 10. Oxygen to carbon methyl migration in the reaction of trimethyl phosphite with dimethyl acetylenedicai boxylate, J. Org. Chem., 30. 2829, 1965. 

Deprotonation of allyl tetramethylphosphorodiamidate, readily prepared from allyl alcohol, induces the migration of phosphorus from oxygen to carbon. A second deprotonation then occurs to give the dianion (33 Scheme 16). Alkylation with 1-iodopropane takes place at the 7-position to give hexanoic acid after hydrolysis. Reaction of (33) with aldehydes and ketones followed by hydrolysis gives 7-lac-tones, and a similar sequence with epoxides produces 6-lactones. 

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