The absolute structure of (+)-strigol

Abstract

The absolute structure of the potent seed germination stimulant (+)-strigol has been established by resolution of racemic strigol via the corresponding N-[(R)-1-(1-naphthyl)ethyl]carbamate and X-ray crystallographic analysis.Strigol (1) was isolated from root exudates of cotton (Gossypium hirsutum L.), and the relative structure was established by Cook and co-workers.1 Strigol exhibited

Germination stimulants produced by Vigna unguiculata Walp cv Saunders Upright

“…The new compound was termed alectrol because of its high germination activity for seeds of Alectra vogelii and the presence of an alcoholic functional group in its structure, as described below. The absolute structure of (+)-strigol is known from its determination by x-ray crystallographic analysis (Brooks et al 1985). To elucidate the chemical structure of alectrol, we compared the spectroscopic and spectrometric data with those of (+)-strigol.…”

“…Its structure and the absolute configuration have been determined (Cook et al 1972, Brooks et al 1985. Many strigol analogs have been synthesized since then; the most active are termed GR-compounds (GR, germination releaser) (Johnson et al 1981).…”

Biosynthetic considerations could assist the structure elucidation of host plant produced rhizosphere signalling compounds (strigolactones) for arbuscular mycorrhizal fungi and parasitic plants

“…2. Hydroxylation at the allylic position in 5-deoxystrigol (3) can occur either without e as in the formation of strigol and orobanchol e or with the migration of the double bond leading to different compounds (10) and (25) (Fig. 6).…”

“…6, compound (1) and compound (4) have already been identified as strigol and orobanchol, respectively. Compound (10) was previously suggested to be alectrol [34], which was excluded on the basis of mismatching spectra of the synthetic structure and the natural alectrol [29,32]. Muller et al also considered the structure with the gem-methyl groups at C-5 instead of at C-8 (12) (Figs.…”

An Efficient Enantioselective Synthesis of Strigolactones with a Palladium-Catalyzed Asymmetric Coupling as the Key Step

“…[14] Over the years extensive efforts have been made to prepare natural and synthetic stimulants in an enantiopure form. The basic strategies reported hitherto for the synthesis of stereohomogenous strigolactones are: i) resolution of the racemic stimulant at the final stage by covalent coupling with a suitable resolving agent [15] or by chromatography on a chiral column, [6,9,16] ii) coupling of the enantiopure ABC fragment [10a,17Ϫ19] with the racemic D-ring precursor and subsequent chromatographic separation of the thus-obtained diastereomeric mixture, iii) coupling of the racemic ABC fragment with an enantiopure D-ring precursor [10b,20,24] and subsequent separation of the resulting diastereomers, and iv) by using starting materials from the chiral pool for the synthesis of an enantiopure ABC fragment. [21Ϫ23] Note that the B and C rings in strigolactones always have a cis relationship, because the trans structures are too highly strained.…”