866222-56-2

Upstream product

• 365236-17-5 phenyl-6-O-acetyl-2,3-di-O-benzyl-4-deoxy-4-C-ethynyl-1-thio-α-D-glucopyranoside 

Downstream Products

• 866222-57-3 4,4'-(buta-1,3-diyne-1,4-diyl)bis(phenyl 2,3-di-O-benzyl-4-deoxy-1-thio-α-D-glucopyranoside) 

Relevant academic research and scientific papers

Functionalised bicyclic exo-glycals by alkynol cycloisomerisation of hydroxy 1,3-diynes and hydroxy haloalkynes

Functionalised bicyclic exo-glycals are readily obtained by base-catalysed (typically MeONa in MeOH) alkynol cycloisomerisation of ethynylated cyclic saccharides. Thus, base treatment of the phenylethynyl- and halogenoethynylated 1-O-acetyl-ribofuranoses 22-24 and the 4-ethynylated 1-thioglucopyranosides 30-33 gave - after deacetylation - selectively the (Z)-configured exocyclic enol ethers 26-28 (84-91%) and 34-37 (63-76%), respectively, resulting from a trans-5-exo-dig cyclisation. The ring closure to the trans-dioxahexahydroindans 34-37 is favoured by a concerted intramolecular protonation of the intermediate vinyl anion by the neighbouring HO-C(3). Cycloisomerisation of the 6-O-acetyl-4-(phenylethynyl)-1-thio-α-D-glucopyranoside 39 occurred via the corresponding phenylethynylated allenes to provide the galacto-configured (Z)- and (E)-cis-dioxahexahydroindans 40 (30%) and 41 (51%). Surprisingly, the HO-C(4) unprotected α-D-galactopyranosyl-buta-1,3-diyne 15 and the β-D-glucopyranosyl-buta-1,3-diyne 51 (and its 2-bromoethynyl analogue) undergo a 6-exo-dig ring closure to the 2,5-dioxabicyclo[2.2.2]octanes 16-19 and 52/53, respectively, the ring closure requiring a boat conformation (B 1,4 for 15, 1,4B for 51). Ring strain (anti-reflex effect) prevents an alkynol cycloisomerisation of 4-(phenylbuta-1,3-diynyl, bromoethynyl, or iodoethynyl)levoglucosan 56-59, and 56 reacted by elimination to the hex-1-ene-3,5-diyne 59 (82%), while isomerisation of 57 and 58 led to epimeric mixtures of the haloallenes 60 (82%) and 61 (68%).