Formal Total Synthesis of (+)-Salicylihalamides A and B:  A Combined Chiral Pool and RCM Strategy

Abstract

The formal total synthesis of the (+)-salicylihalamides A and B is detailed, utilizing a chiral pool approach to generate the three stereogenic centers and a ring-closing metathesis (RCM) for the formation of the macrocyclic ring structure. Starting from a known glucose-derived alcohol, the formal total synthesis was achieved in an efficient 13-step protocol in 26% overall yield. It was found that substitution at the remote phenolic group significantly influenced the ratio of the E- and Z-double bond products in the RCM step. The introduction of phenol protecting groups provided E-isomers preferentially and also enhanced the rates of the RCM reactions.

Fast and Scalable Route to Aryl Polyallyl Dendrons and Dendrimers

“…[18] When the protected 4-methoxytriallylmethylbenzene (2c) was treated with tetrabutylammonium iodide and boron trichloride from À78 8C to room Scheme 2. Organic approach to 4-triallylmethylphenol dendron (2).…”

“…The allylation of the readily ionizable 3b with allyltrimethylsilane in a solution of BF 3 in dichloromethane gave the naphthol protected 6-methoxy-2-triallylmethylnaphthalene 3c in 90% yield. The deprotection of the phenol group in 3c in the presence of (n-Bu) 4 NI/ BCl 3 [18] led to the 6-triallylmethyl-2-naphthol dendron (3) in 92% yield.…”

Enantiospecific Synthesis and Cytotoxicity Evaluation of Oximidine II Analogues

“…In agreement with previous trends [26,27] and our design rationale, reactiono fseco-cycle 16 using the Grubbs secondgeneration ruthenium catalystp roduced diene macrocycle 18 in 60 %y ield over two steps (from 14). Oxidative cleavage of the para-methoxybenzyl (PMB) ether,o xidation of the resultant primarya lcohol to the corresponding aldehyde, followedb y aH orner-Wadsworth-Emmons (HWE) olefination with phosphonate 26 installed the desired vinyl sulfone unit.…”

Synthesis of a Benzolactone Collection using Click Chemistry

“…[20] In comparison, deprotonation of the alkyne 10 with nBuLi followed by trapping of the anion with triisopropylsilyl chloride provided the benzoate 2 in 78 % yield. [18] Nevertheless, the direct condensation of alkynol 7 with acid [21] 9 still was the best option.…”

“…The residue was purified by flash chromatography (petroleum ether/ethyl acetate, 9:1) to provide the desired alkynol 8 (89 mg, 90 %) as a colorless wax. 31 mmol) and triphenylphosphane (4.84 g, 18.47 mmol, recrystallized from methanol) in toluene (45 mL) was added dropwise a solution of acid [21] 9 (6.62 g, 34.46 mmol) and diisopropyl azodicarboxylate (DIAD) (3.64 mL, 3.74 g, 18.47 mmol) in toluene (20 mL). After 1.5 h of stirring at room temperature, the solvent was removed in vacuo and the residue purified by flash chromatography (petroleum ether/ethyl acetate, 15:1).…”