Investigation of the Diels−Alder Cycloadditions of 2(H)-1,4-Oxazin-2-ones

Abstract

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Transition metals in organic synthesis: Highlights for the year 2005

“…Examples of ring systems include, bromooxabicyclo[3.2.1]octadiene [28], 5-trifloxyindoles [29], 6-halopurines [30] and 3,5-dichloro-2(H)-1,4-oxazin-2-one [31]. A palladium-catalyzed coupling of a 2-thiomethylbenzoxazole with a 2-pyridyltin reagent was used in a synthesis of pyridinyl boxazomycin C analogs [32].…”

Synthesis of a Pseudo-Disaccharide Library and Its Application to the Characterisation of the Heparanase Catalytic Site

“…Our group has pioneered the application of Diels-Alder cycloadditions[ 16 , 17 , 18 , 19 ] to the synthesis of pseudomonosaccharides (carbasugars[ 20 ] and azasugars[ 21 ]), pseudodisaccharides[ 22 , 23 ], and other complex organic molecules[ 24 ]. Recently, we have applied this methodology to an efficient and divergent synthesis of a set of pseudomonosaccharides 5 , 6 and 7 ( Figure 2 ), to explore the role of a basic group at the pseudoanomeric position of glycosyl hydrolase enzymes, and demonstrated the usefulness of these molecules in probing the enzyme binding pocket at the anomeric position of mannosidase enzymes[ 25 ].…”

Application of 1,4-Oxazinone Precursors to the Construction of Pyridine Derivatives by Tandem Intermolecular Cycloaddition/Cycloreversion

“…We hypothesized that the underutilized nature of oxazinones related to 1 was attributable not to reactivity but to the limited methods available to prepare them. Excluding two examples, 1,4-oxazinones have been prepared from cyanohydrin derivatives in the presence of excess oxalyl chloride at elevated temperatures (>90 °C). , This method, though direct, suffers from use of toxic cyanohydrin starting materials, harsh reaction conditions, and modest yields for some derivatives (in particular 4a ) and necessarily produces the 3,5-dichloro substitution (eq 1, Figure ). Although further derivation of 3,5-dichlorooxazinones is possible at the more reactive 3-position through palladium or S N Ar chemistries, room for improvement and additional methods for the construction of 1,4-oxazinones is evident.…”

“…We sought to explore an alternative route that utilized α-amino acid derivatives as starting materials for the construction of 3,5-carbon-substituted oxazinone substrates. Because precedent for cycloaddition of such carbon-substituted oxazinones is limited, we hoped a new synthesis of these derivatives would enable exploration of the reactivity and selectivity in the tandem cycloaddition/cycloreversion sequence . To this end, the goals of pyridine synthesis were to confirm the reactivity of substituted oxazinones with terminal alkyne precursors and discern baseline regioselectivity trends.…”