Reaction of allylic aluminum reagents with 1,3-dithienium tetrafluoroborate and with 2-chloro-1,3-dithiane: preparation of 2-substituted 1,3-dithianes

Abstract

This observation refers to an equilibrium reaction involving the pyridylthio radical, i.e., cleavage of the carbon-sulfur bond of 1, which also applies to the reaction of 1 with 2

Total Synthesis of 17-isoLevuglandin E4and the Structure of C22-PGF4α

“…20 All reactions conducted in an inert atmosphere were in argon unless otherwise specified. 2(Z)-1-(2-Tetrahydropyranyloxy)-5-iodopentene (1), 37 isopropylidene-D-glyceraldehyde (9), 38,39 1,1-diethoxybut-3-yne (11), 40 and trans-bis(tri-n-butylstannyl)ethylene (19) 32 were prepared by literature procedures. Methyl 4-oxobutanoate (3) was also prepared by a literature procedure 41 except that pyridinium chlorochromate (1.4 equiv) was used as oxidant instead of pyridinium dichromate.…”

“…The solvent was removed by rotary evaporation under reduced pressure, and the residue was chromatographed on a silica gel column with 50% ethyl acetate in hexanes to afford the pure alcohol 5 (536 mg, 98% yield); 1 H NMR (CDCl3, 300 MHz) δ 5.64 (dt, 1H, J ) 4.0 Hz, J ) 8.4 Hz, C8-H), 5.37-5.47 (3H, C7, C4, C5-H), 4.23 (d, 2H, J ) 6.6 Hz, C9-H), 3.68 (s, 3H, OCH3), 2.84-2.87 (dd, 2H, J ) 5.3 Hz, J ) 5.6 Hz, C6-H), 2.36-2. 40 Methyl 9-Bromonona-4(Z),7(Z)-dienoate (6). To a magnetically stirred solution of alcohol 5 (534 mg, 2.90 mmol) in anhydrous CH 2Cl2 (60 mL) at 0 °C was added CBr4 (1.16 g, 3.48 mmol, 1.2 equiv) and DIPHOS 43 (1.39 g, 3.48 mmol, 1.2 equiv) portionwise over 15 min.…”

Direct Regioselective [3 + 2]-Cyclization Reactions of Ambivalent Electrophilic/Nucleophilic β-Chlorovinyl Dithianes: Access to Cyclopentene Derivatives

“…Among various types of organic reagents, dithiane compounds serve as valuable umpolung intermediates in the field of synthetic organic chemistry because of their unique properties and reactivities. − Recently, the demonstrated ambivalent donor–acceptor (D–A) reactivities of β-chlorovinyl dithianes in our group have opened up a novel class of reaction pathways beyond the typical dithiane methods . The development of [3 + 2]-cycloaddition has been achieved through identification of reactive vinylidene dithiane species and aldehydes .…”

Diastereoselective Synthesis of Homoallylic Alcohols with Adjacent Tertiary and Quaternary Centers by Using Functionalized Allylic Aluminum Reagents

“…[5] The preparation of unsaturated aluminum organometallic compounds from commercial aluminum powder is in general difficult, but a proper activation of the aluminum surface allows an effective insertion of aluminum into aryl halides. [6] Previously, allylic aluminum reagents were prepared from allylic bromides by the methods of Gaudemar et al [7] and Miginiac et al [8] using diethyl ether as the solvent and in the presence of a catalytic amount of HgCl 2 . Herein, we wish to report a practical synthesis of functionalized allylic aluminum reagents bearing an aryl, an ester, or a cyanide substituent by the insertion of commercial aluminum powder into various allylic chlorides or bromides in the presence of a catalytic amount of InCl 3 .…”