The synthesis of 1,2:5,6-di-O-isopropylidene-d-mannitol: a comparative study

A High Yield Synthesis of 1,2:5,6-Di-O-Isopropylidene-D-Mannitol

“…The volatile diethyl ether was evaporated in the rotary evaporator without heating and the white residue was washed with hexane resulting in the diacetal (2) (87% yield). TLC, GC-MS, 1 H and 13 C NMR showed that the white solid presented a very minor amount of the less polar triacetal (5%). It has been used without any further purification, for the synthesis of 2,3-O-isopropylidene-Dglyceraldehyde (3) 2,3 .…”

“…Nevertheless two other research groups have repeated this procedure in yields of only 36-40% 13,14 .…”

Synthesis of Two Diastereomeric C1–C7 Acid Fragments of Amphidinolactone B Using B‐Alkyl Suzuki–Miyaura Cross‐Coupling as the Modular Assembly Step

“…We first examined the methods for accessing the alkenyl iodide (E)-or (Z)-6 with high enantiopurity. The chiral aldehyde 9 readily prepared from 1,2:5,6-di-O-isopropylidene-D-mannitol (8) [17] was used, without column chromatographic purification, for iodomethylenation under two conditions (Scheme 1 and Table 1). [18,19] When the aldehyde 9 was subjected to the Takai reaction [18] using CrCl 2 -CHI 3 in dioxane-THF at room temperature, the expected alkenyl iodides [(E)-6 and (Z)-6] were not obtained; instead, the corresponding diols [(E)-6' and (Z)-6'] were isolated in 60 % combined yield with an E:Z ratio of 79:21 as estimated by 1 H NMR analysis of the product (entry 1, Table 1).…”

Optisch aktive Glycerinderivate

“…Ahnliche Komplikationen beobachtet man auch, wenn die primare Hydroxylgruppe selektiv als Benzoat geschiitzt wird14). Beim Vergleich der drei Wege erscheinen der erste [ausgehend von (8)10)] und der zweite [ausgehend von (9) mit Ar = C6H5I4)] nicht so giinstig, weil die primar eingefiihrten Schutzgruppen wieder abgespalten werden miissen, um das fur die Glykolspaltung notige 3,4-Diol zu gewinnen. Bei der Verwendung von p-Methoxybenzaldehyd fur den zweifachen Schutz von D-Mannit zu (9) (Ar = p-CH30-C6H4) ist es aber moglich, nach Benzylierung der freien OH-Gruppen den 1,3-Dioxolan-Ring so zu offnen, daR die primare OH-Funktion als p -Methoxybenzylether blockiert bleibt [vgl.…”