Synthesis of Vinca Alkaloids and Related Compounds. 90.¹ New Results in the Synthesis of Alkaloids with the Aspidospermane Skeleton. First Total Synthesis of (±)-3-Oxominovincine

Construction of novel spiroisoxazolines via intramolecular cyclization/methylation

“…The syntheses of a variety of isoxazolines was achieved through the 1,3-dipolar cycloaddition of disubstituted geminal alkenes, 1 and 2 ,12 with the requisite nitrile oxide. Compounds 3 a-d and 4 a-d were isolated as a single regioisomer after the respective 1,3-dipolar cycloaddition of 1 and 2 with the corresponding in situ generated nitrile oxidel3 (Scheme 3).…”

Efficient synthesis of allylamines from a novel (E)-2,3-difunctionalized allyl bromide

“…Functinalized allyl [1][2][3][4][5][6] and vinyl bromides [7][8][9][10] are often used as intermediates for the synthesis of biologically active compounds [11][12][13][14][15][16] including natural products. 17,18 Continuing with our efforts directed toward the development of new methodologies for the synthesis of functionalized brominated derivatives, [19][20][21][22][23][24] we describe in this paper an efficient alternative for the preparation of a new family of allyl bromide (E)-4 and vinyl bromide (E)-5 from tetraethyl prop-2-ene-1,2-diyldiphosphonate 2 (Scheme 1) with complete stereoselectivity in favour of the E configuration starting from inexpensive reagents.…”

A Review on Recent Developments in Syntheses of the Post-Secodine Indole Alkaloids. Part I: The Primary Alkaloid Types

“…The tendency of "naturally" configured tetracyclic aminoesters to undergo preferential lactam formation is further illustrated by Szántay et al 46 with their formal total synthesis of (±)-N-acetyl-12-demethoxycylindrocarine (96), whose (-)-enantiomer is contained in Tabernaemontana 48 primary amine 103a as an alternative to amine 69, which permitted isolation of the secodine-type intermediates, Scheme 17. Thus, condensation of rather unstable amine 103a, freshly prepared from the trityl derivative 103b, with aldehyde ester 6 afforded stable, crystalline lactam 104a in 79% yield.…”

“…Thus, condensation of rather unstable amine 103a, freshly prepared from the trityl derivative 103b, with aldehyde ester 6 afforded stable, crystalline lactam 104a in 79% yield. Its conversion to (±)-3-oxovincadifformine (55) was described repeatedly 48,49 ; an alternative synthesis from indole acetate 105a proceeds through 105b, see 50,51 ; Scheme 17. Two procedures for the preparation of stabilised secodine-like intermediate 104b were implemented in the synthesis of (±)-3-oxominovincine 48 (84a), Scheme 17.…”