Functions Bearing Two Oxygens, R12C(OR2)2

MacPherson, David T.; Rami, Harshad K.

doi:10.1016/b0-08-044705-8/00203-x

Cited by 5 publications

(1 citation statement)

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“…Protection of carbonyl groups is widely used in the synthesis of multifunctional molecules, and its many efficient methods were described . Among them, acetalization is a primary solution and was applied from early times. , The general methodology for the acetal formation consists of acid-catalyzed reaction of carbonyl compounds with diols, where the equilibrium of the reaction is shifted by azeotropic water removal or dissicators or by reaction with oxiranes catalyzed by Lewis acids and tetraalkylammonium halides . The last of these reactions proceeds via nucleophilic opening of the oxirane ring with formation of 2-haloethoxide, which subsequently adds to the carbonyl group with the formation of an O-anion of the hemiacetal.…”

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Intermolecular Reactions of Chlorohydrine Anions: Acetalization of Carbonyl Compounds under Basic Conditions

Barbasiewicz

Mąkosza

2006

Org. Lett.

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[reaction: see text] Nonenolizable aldehydes and ketones react with 2-chloroethanol and 3-chloropropanol under basic conditions (t-BuOK, DMF/THF) with formation of 2-substituted 1,3-dioxolanes and 1,3-dioxanes, respectively. Conversion of the two-step addition-alkylation process depends on the electrophilicity of the carbonyl group that governs the equilibrium of addition of chloroalkoxides. This method of protection of carbonyl groups in the form of cyclic acetals under kinetically controlled conditions is complementary to the acid-catalyzed reaction with diols.

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Intermolecular Reactions of Chlorohydrine Anions: Acetalization of Carbonyl Compounds under Basic Conditions

Barbasiewicz

Mąkosza

2006

Org. Lett.

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Synthesis of the (+)‐C26–C40 Domain of the Azaspiracids by a Novel Double Intramolecular Hetero‐Michael Addition Strategy

Hao

Aiguadé

2001

Angewandte Chemie

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The azaspiracid natural products (AZA 1 ± 5, ) are causative agents of human poisonings associated with the consumption of shellfish that were first recognized in the Netherlands in 1995. [1] Originally isolated from the mussel Mytilus edulis cultivated in Killary Harbor, Ireland, the azaspiracids have since been detected in a growing range of aquatic organisms and geographical locations. Physiological aspects of azaspiracid poisoning (AZP) are distinct from those of other known shellfish intoxications. These include delayed onset and prolonged duration of acute symptoms, and necrosis of the intestine, thymus, and liver. Hence, the azaspiracids represent an emerging new class of environmental toxins with serious economic and human health consequences. As a result there is an urgent need of authentic samples for continued environmental monitoring.Structurally, the azaspiracids are complex w-amino acids that contain within their 40-carbon backbone an unprecedented array of polycyclic, spiro-fused ring systems. Among the members of this class reported to date, minor variations in skeletal substitution occur within the C1 ± C25 domain, but the C26 ± C40 portion remains constant. The relative stereochemistries within the C6 ± C25 and C28 ± C40 domains of the azaspiracids have been assigned, but neither the stereochemical relationship between these two regions, nor the absolute stereochemistry of either has been established. These factors molecular architectures in electronic devices in which the well-defined character of p-conjugated oligomers is combined with the material properties of polymers Experimental SectionBOPVUP: Under an argon atmosphere, diisocytosine compound 2 (0.03 g, 0.07 mmol) was dissolved in anhydrous pyridine (5 mL) and heated to 90 8C. A solution of OPV-isocyanate 1 (0.20 g, 0.15 mmol) in anhydrous pyridine (10 mL) was added and the reaction mixture was stirred overnight at 90 8C. The solution was subsequently cooled to room temperature and the pyridine was removed by evaporation under vacuum. The residue was purified by column chromatography (silica gel, ethyl acetate then CH 2 Cl 2 to remove impurities and finally CH 2 Cl 2 /MeOH (97/3, v/v) to collect the desired product) to afford BOPVUP as an orange solid (95 mg; 45 % yield). UV/Vis (CHCl 3 ): l max (e) 432 nm (258 000 m À1 cm À1 ); (m), 963 (s), 916 (w), 850 (m); MALDI-TOF MS (M r 3062.62) m/z: 3063.29; elemental analysis calcd (%) for C 196 H 306 N 8 O 18 (M r 3062.[1] For examples see:

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