Syntheses via vinyl sulfones. 11. A triply convergent total synthesis of L-(-)-prostaglandin E2

Abstract

Riccardin A Diacetate (2). Riccardin A (1, 40 mg) was dissolved in 3 mL of pyridine and 3 mL of acetic anhydride. The mixture was allowed to stand overnight. The reaction mixture was treated in usual manner to give riccardin A diacetate (2): 45 mg; mp 209-210 °C (from petroleum ether); UV 218 nm (log

Facile regeneration of carbonyl compounds from oximes under microwave irradiations using N-bromophthalimide

“…Secondly, oximes may be accessed by routes not involving the carbonyl function such as the Barton reaction and the reduction of nitro compounds, 3 and so subsequent hydrolysis would define a route to the parent carbonyl compounds. A good number of methods based on hydrolytic, 4 reductive, 5 and oxidative, 6 reactions have been developed for deoximation. In spite of the many reagents available, there is still scope for newer reagents as the existing oxidative methods suffer from one or the other disadvantages like long reaction times, 7 difficulties in isolation of products, 8,9 and formation of over oxidation products leading to low yields.…”

Selective Regeneration of Carbonyl Compounds from Oximes with N-Bromosuccinimide Under Neutral and Mild Conditions

“…Moreover, since oximes can be prepared from non-carbonyl compounds [3], the regenerated carbonyl compounds from oximes provide an alternative method for the preparation of aldehydes and ketones. Most of the known methods of regenerating carbonyl compounds from their nitrogen derivatives require strongly acidic [4], oxidative [5], or reductive [6] conditions. Recently, clay supported ferric nitrate [7], dimethyl dioxirane [8], pyridinium dichromate-t-butyl hydroperoxide [9], iodosobenzene diacetate [10], the titanium silicalite-1-H 2 O 2 combination [11], and 70% TBHP [12] have been reported to cleave the C=N bond of oximes and tosylhydrazones.…”

Epoxy derivatives of {(5-[(1-Phenylethyl)aminocarbonyl]-cyclopent-2-en-1-yl}methyl acetates

“…In the 1 H NMR spectrum of cis-epoxide V, the 2-H signal (δ 3.03 ppm) is located in a weaker field (see figure) than the corresponding DOI: 10 . This is the result of through-space electron-withdrawing effect of the oxirane oxygen atom on the vicinal 2-H proton in trans isomer VI.…”

“…Although allylic BocNH and trichloroacetamide groups, as well as homoallylic hydroxy group, are known to act as cis directors in the epoxidation of cyclopentene systems with m-chloroperoxybenzoic acid [8][9][10], the corresponding effect in dihomoallylic amides IVa and IVb is insignificant. Presumably, the stereoselectivity in the epoxidation of IVa and IVb is determined not only by the effect of heteroatom but also by steric factors, which act in the opposite directions.…”