A simple and efficient PdCl2 mediated conversion of γ,δ-olefinic alcohols into C-glycosides

Synthesis of pseudo saccharide precursors through ‘off template site’ Michael –Wittig reaction on sugar derived enal

“…Such a conformation for the carbocycle ring is again energetically favored, as apart from substituent at C-6 and C-9, all the substituents are placed equatorial. For compound 4 the characteristic NOE cross peaks H6-H10a and H5-H9 as well as large value of about 10 Hz for J 9, structure and conformation are supported by strong NOE cross peaks between H5-H7, H8-H10a and J 5, 10a and J 7,8 of about 10 Hz . The six membered rings in all these molecules take 8 C 5 chair conformation.…”

“…Thus, development of novel and efficient methods for the enantioselective or enantiospecific construction of carbocycles 6 resulted in a variety of useful routes such as Diels-Alder approaches, the double Michael cyclisation, 1,3-dipolar cycloaddition and free radical-induced C-C bond formation. As part of our ongoing efforts on the transformation of monosaccharides into new glycosubstances [7][8][9][10][11][12][13][14][15] , herein we describe the synthesis of C-C linked pseudo saccharide precursors 1-5 ( Figure 1), adopting a Michael-Wittig reaction on sugar-derived enal. …”

Effect of the allylic substituents on ring closing metathesis: the total synthesis of stagonolide B and 4-epi-stagonolide B

“…16 Selective 1 • -OH tosylation of 17 followed by base treatment furnished the epoxide 19. 17 Opening of the oxirane by using EtMgBr needed some experimentation, as the formation of the corresponding bromohydrin was the competing reaction. Under optimized conditions, we could isolate the requisite coupling partner 9 in 71% yield, with identical spectral and analytical data to that reported earlier.…”

Palladium‐Catalyzed Aerobic Synthesis of Terminal Acetals from Vinylarenes Assisted by π‐Acceptor Ligands

“…The direct synthesis of acetals from alkenes and alcohols is a useful method that involves two steps formally, that is, the oxidation of alkenes to aldehydes or ketones and their protection . Although Markovnikov selectivity is mainly observed in the Pd‐catalyzed intramolecular acetalization and hemiacetalization of alkenols, intermolecular acetalization of alkenes that have an electron‐withdrawing group or a directing group proceeds selectively in an anti‐Markovnikov manner to give terminal acetals. As for vinylarenes, internal acetals are formed by using a PdCl 2 (sparteine)/CuCl 2 catalyst system under O 2 , whereas terminal acetals are obtained by other Pd, Fe, and I catalyst systems (Scheme ).…”