Total synthesis of (+)-virgatusin via AlCl3-catalyzed [3+2] cycloaddition

Abstract

The AlCl(3)-catalyzed cycloaddition of a donor-acceptor (don-acc) cyclopropane and piperonal succinctly provides the core of virgatusin in a selective, high-yielding manner.

Asymmetric Total Synthesis of the Indole Diterpene Alkaloid Paspaline

“…Guided by our previous work in developing symmetry-breaking processes to enable rapid construction of complex natural products, 15g,h we surmised that a synthesis beginning from desymmetrization of a paspaline E ring precursor might circumvent the problems associated with our initial strategy. It is important to note at this juncture that Smith’s synthesis of 1 also commences via a symmetry-breaking process; 12a namely, the Wieland–Miescher ketone synthesis ( 28 → 34 ) assembles the D–E ring fusion of 1 concomitant with the C12c quaternary stereocenter.…”

“…Subsequent partial 13 and total 14 synthetic studies of these molecules have since been disclosed, building on these advances. As an extension to previous work in our laboratory in developing total synthesis platforms for complex molecular frameworks, 15 we sought to develop an expedient synthesis of 1 , particularly of the key C4a, C12b, and C12c stereocenters, which could serve as a template for assembly of the remaining structures in this family. Our work toward this goal culminated in a highly stereocontrolled total synthesis of paspaline.…”

Ein neues goldenes Zeitalter in der Chemie Donor‐Akzeptor‐substituierter Cyclopropane

“…Für den DyKAT-Prozess kam ein (pybox 2 *)Mg II -Katalysator zum Einsatz, der einerseits die innere Umwandlung des als Racemat eingesetzten Cyclopropyl-Substrats vermittelte und andererseits die Reaktion nur eines Enantiomers mit dem Aldehyd katalysierte (Tabelle 4, Nr. So konnten die Naturstoffe (+)-Virgatosin, [46] (À)-Allosecurinin, [47] (+)-Isatisin A [48] und (+)-Polyanthellin A [49] mithilfe solcher Cycloadditionen hergestellt werden. [36] Bei Reaktionen von D-A-Cyclopropanen, die zwei Donor-Substituenten aufweisen, wurden bevorzugt Produkte des Typs 43 b gebildet, bei denen der sterisch anspruchsvollere Donor (D L ) cis-ständig zum Aldehyd-Rest R L angeordnet war (Tabelle 4, Nr.…”

Theoretical studies on vibrational spectra of some aluminum halides: Effect of theoretical methods and basis sets

“…For example, aluminum trichloride (AlCl 3 ) as a Lewis acid plays a major role as catalyst in the Friedel-Crafts alkylation and acylation of aromatic rings reactions [1,2]. AlI 3 , frequently used to promote the cleavage of epoxides [3] and esters cleavage [4], is a good carrier material for chemical transport reactions [5,6], a good starting material for the preparation of aluminum nitride, AlN, which is a ceramic material with excellent thermal conductivity and many other attractive properties [7,8].…”