Gamer s aldehyde

In the dihydroxylation of cyclohexene by Me3N+—O-, catalysed by OsC>4, aromatic amines and aliphatic chelating (TMEDA) or bridging (DABCO, hexamine) amines were found to retard the oxidation, owing to the formation of amine adducts of the dioxomonoglycolatoosmium(VI) ester intermediates, which are more resistant to the further oxidation required for product formation.98 Alkenes derived from Gamer s aldehyde, A-Boc-/V,0-acctonide of the aldehyde of L-serine, may be dihydroxylated by OsC>4 with excellent selectivities that may be explained by A1,3 strain.99... 

A variety of imine derivatives have been used in these processes including those derived from norephedrine (25) <00TA4639>, Gamer s aldehyde (26) <03TL527> (in this case the required... 

A short asymmetric synthesis of the 2-ketocarbacepham (27) involving as the initial step for the preparation of the starting piperidone, a hetero Diels-Alder reaction of the benzylimine derived from the enantiomer of Gamer s aldehyde with Danishesky s diene, has been described <02JOC598>. The key cyclization step to form the bicyclic P-lactam system was achieved from a P-amino acid precursor using the Mukaiyama reagent, 2-chloro-A-methylpyridinium iodide. 

A highly anti-selective hydrocyanation of (7 )-jV-Boc-2, 2-dimethylthia-zolidine-4-carbaldehyde (Gamer s aldehyde) with hydrogen cyanide in the presence of a Lewis acid has been reported [78]. In the initial study, we applied the procedure to the synthesis of anti-O-TMS cyanohydrin 23. However, the cyanosilylation of 22 in the presence of Lewis acid such as zinc iodide (Znl2), zinc bromide (ZnBr2) or boron trifluoride (BFy) diethyl ethcrate was problematic, leading only to traces of 23. 

Konas, D. W., Pankuch, J. and Coward, J. K. (2002) The synthesis of (25)-4,4-difluoroglutamyl y-peptides based on Gamer s aldehyde and fluoro-Reformatskii chemistry. Synthesis, 2616-2626. 

Asymmetric 1,3-DC of ynolates with a nitrone derived from Gamer s aldehyde afforded 5-isoxazolidinones in good yields and with high diastereoselectivity. The adducts were alkylated and converted to enantiopure P-amino acids, P-lactams and y-lactams <05TA2821>. 

EDCI), the nitrogen and hydroxyl groups were protected as the N,0-acetal 1233 by reaction of 1232 with 22-dimethoxylpropane in acetone in the presence of trifluoroborane etherate. Finally, reduction of the N-methoxyamide with lithium aluminium hydride afforded Gamer s aldehyde in 88% overall yield for the 4-step sequence, Epimerisation of the stereogenic centre is negligible under these conditions. 

In 2009, Marco et al. reported the synthesis of hyacinthacine A2 7 and A3 8 and unnatural isomer 5- p/-hyacinthacine A3 118 from the intermediate 119, issued from the (/ )-Gamer s aldehyde, a derivative of L-serine [38]. Alcohol 119, obtained in six steps from Gamer s aldehyde [39], was first protected as a TES ether, then submitted to an oxidative cleavage of the terminal alkene to provide the alcohol 121 after subsequent reducticm step. Desilylation followed by mesylation afforded the compound 123, which underwent a one-pot acidic cleavage of the Boc and aminoketal protective groups. Standard hydrogenoly-sis of benzyl ethers and cyclization under basic conditions achieved this linear but efficient synthesis of hyacinthacine A2 (14 steps from Gamer s aldehyde, 22% overall yield) (Scheme 34). 

In order to synthesize alkyne 223, enantioenriched ethynylaziridme 220 was prepared by a known four-step sequence (762) from (S)-Gamer s aldehyde (765,164). A reductive coupling reaction (765,166) of the aziridine 220 with formaldehyde in the presence of Pd(Ph3)4 and Inl furnished the 2-ethynyl-l,3-amino alcohol 221. Protection of 221 as benzylidene acetal gave the alkyne 222, which was converted in the next step to the corresponding iodoalkyne 223 (767). 

Gamer s aldehyde (N-Boc-2,2-dimethyloxazolidine-4-carbaldehyde) as a versatile intermediate in the synthesis of enantiopure natural products 13BJ02641. 

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