Synthesis of Dihydrofurans and Dihydropyrans with Unsaturated Side Chains Based on Ring Size‐Selective Ring‐Closing Metathesis

Abstract

Enantiomerically pure 1,5-hexadiene-3,4-diol, derived from d-mannitol in a few steps, may serve as a starting material for enantiopure dihydropyrans and dihydrofurans bearing an unsaturated side chain which is amenable for further synthetic transformations. The synthesis relies on a ring sizeselective ring-closing metathesis reaction of a triene. Most likely, a catalyst-directing effect of an allylic hydroxy group is responsible for the selectivity.

Synthesis of 3‐Deoxy Glycals via Tandem Metathesis Sequences and Their Use in an Intermolecular Heck Arylation

“…Formation of benzyl ether 6 has previously been described in the literature. [47,49] Vanadiumcatalysed epoxidation of 6 was investigated in different context by us. [50] The reaction yields epoxide 7 [50] in good yield and perfect regioselectivity within short periods of time.…”

“…[ [45][46][47] is conveniently available from -mannitol in few steps. Interestingly, the (S,S)-enantiomer of this compound is also available in few steps from -tartrate.…”

“…Optical purities were determined by HPLC using a HP-LC-1050 system equipped with a Daicel Chiralcel OD column. The following compounds have been prepared following procedures described in the literature: 6, [47,49] 7, [50] 8, [50] 14. …”

A Cross‐Metathesis–Conjugate Addition Route to Enantiopure γ‐Butyrolactams and γ‐Lactones from a C2‐Symmetric Precursor

“…Diol 1 has been used in target molecule synthesis, [7][8][9][10][11][12][13][14][15][16][17][18][19] as a chiral diene ligand in asymmetric catalysis, [20] and as a probe for catalyst directing effects by hydroxy groups in ring-closing metathesis (RCM) reactions. [6,21,22] The enantiomer, ent-1, has been synthesized by Blechert and co-workers from d-(-)-tartrate and employed in the total synthesis of phomopsolide by using cross metathesis and a subsequent RCM step. [23] In this and many other cases, desymmetrization of 1 or ent-1 is achieved by monofunctionalization of one OH group, often with a bulky protecting group.…”

“…[1] C 2 -Symmetric building blocks are particularly useful because they have homotopic functional groups and can be desymmetrized by selective monofunctionalization. [2] Accordingly, (3R,4R)-hexa-1,5-diene-3,4-diol (1), which is available from d-mannitol in a few steps, [3][4][5][6] is a very useful ex-chiral-pool starting material. Diol 1 has been used in target molecule synthesis, [7][8][9][10][11][12][13][14][15][16][17][18][19] as a chiral diene ligand in asymmetric catalysis, [20] and as a probe for catalyst directing effects by hydroxy groups in ring-closing metathesis (RCM) reactions.…”