John K. Gallos

d- and l-Erythrose as sources of chiral quaternary carbon centers. Total synthesis of (−)-malyngolide and (+)-tanikolide

Abstract A highly efficient and versatile approach was applied for the total synthesis of the marine natural products (−)-malyngolide and (+)-tanikolide from isopropylidene l - and d -erythrose, using a common strategy.

The hetero-Diels-Alder addition of ethyl 2-nitrosoacrylate to electron-rich alkenes as a route to unnatural α-amino acids

Abstract A new method for the stereoselective synthesis of nonproteinogenic α-amino acids has been developed, which involves hetero-Diels–Alder addition of ethyl 2-nitrosoacrylate to electron-rich alkenes, such as enol ethers, enamines and allylsilanes, and a further two or three step manipulation of the resulting oxazines.

A new total synthesis of pentenomycin

Abstract A new total synthesis of enantiomerically pure pentenomycin has been achieved by the intramolecular nitrone cycloaddition of the proper γ-unsaturated aldehyde, easily accessible from l -arabinose, followed by reductive NO bond cleavage and further oxidative deamination of the resulting aminocyclopentitol.

Expeditious synthesis of seven-membered iminocyclitols

Abstract A concise synthesis of an azepanetriol and an octahydropyrrolo[1,2-a]azepinepentol, by nitrone addition to a pent-4-enofuranoside derived from d -ribose, followed by reductive opening of the isoxazolidine ring formed, is reported.

Diastereocontrol in the intramolecular cycloadditions of 2-substituted-erythro-3,4-isopropylidenedioxyhex-5-enenitrile oxides

Abstract The influence of the 2-substituent on the diastereoselectivity of the intramolecular cycloadditions in a series of 2-substituted-erythro-3,4-isopropylidene-dioxyhex-5-enenitrile oxides, generated in situ from selected sugar derivatives, was examined.

Hetero-Diels–Alder additions to pent-4-enofuranosides: concise synthesis of hydroxylated pyrrolizidines

Abstract A new facile method for the synthesis of hydroxylated pyrrolizidines of the alexine family has been developed, which involves hetero-Diels–Alder addition of ethyl 2-nitrosoacrylate to pent-4-enofuranosides and a further two-step reductive ring opening-ring closure treatment of the cycloadduct.

A new entry to hydroxylated pyrrolizidines

Abstract A short and efficient synthesis of (1 R ,2 S ,5 R ,8 S )-5-hydroxymethyl-1,2-dihydroxypyrrolizidine 1 , by hetero -Diels–Alder addition of a nitrosoalkene to a pent-4-enofuranoside derived from D -ribose, followed by reductive opening of the oxazine ring formed, is reported.

Oxo-bridged compounds of iodine(III): syntheses, structure, and properties of µ-oxo-bis[trifluoroacetato(phenyl)iodine]

The title compound has been prepared by using several approaches. It reacts with both strong bases and acids and is an oxidant. Its crystal structure has been determined from four-circle diffractometer data (R = 0.043). The primary iodine geometry is T-shaped [O–I–O = 172.7(3)o], with shorter I–O (bridge) than I–O(acid)[2.017(7) and 2.272(8)A avg., respectively]. Secondary bonds have I ⋯ O of 2.929(8)A to 3.273(8)A.

Reactions of furoxans with phosphorus ylides

Abstract Benzofuroxan ( 1 ) reacts with phosphorus ylide 2 to give benzimidazole derivatives 8 and 10 , Whereas reaction of 1 with ylide 12 furnishes quinoxaline 17 via an Initial Wittig-type reaction. Similarly the reaction between the furoxano[3.4-b]quinoxalines 19a or 19b and the ylide 2 yielded compounds 22a and 22b , respectively. In these reactions as well as in the reactions of the above furoxans with other phosphorus ylides, a significant deoxygenation of the furoxans to furazans with subsequent oxidation of the ylides is generally observed.

Bicyclo[3.1.0]hexanes from sugar-derived diazo compounds and iodonium ylides. Diastereocontrol and synthetic applications

Abstract The CuI and Rh 2 (OAc) 4 catalyzed decomposition of ethyl 2-diazo-4,5-isopropylidenedioxy-3-oxo-6-heptenoate results in intramolecular cyclopropanation products with opposite diastereoselectivity. In contrast, decomposition of the respective iodonium ylide can proceed without catalysts to give the cyclopropanation products with diastereoselectivity unchangeable by the presence of CuI and Rh 2 (OAc) 4 , revealing thus, that in this particular case the reaction is an electrophilic addition of the iodonium center to the double bond. The synthetic importance of these reactions has been demonstrated by preparing a number of precursors of cyclopentyl, cyclopropyl and bicyclo[3.1.0]hexyl antiviral carbocyclic nucleosides.