ChemComm
Communication
R. S. Paton, J. Am. Chem. Soc., 2012, 134, 20178–20188 and references
cited therein.
For two recent accounts of research in the arena see: (a) T. Mart ´ı n,
J. I. Padr o´ n and V. S. Mart ´ı n, Synlett, 2014, 12–32; (b) D. Kim, Synlett,
5
6
2014, 33–57.
For recent representative examples see: (a) S. Keshipeddy, I. Mart ´ı nez,
B. F. Castillo II, M. D. Morton and A. R. Howell, J. Org. Chem., 2012, 77,
7
883–7890; (b) S. A. Snyder, A. P. Brucks, D. S. Treitler and I. Moga,
J. Am. Chem. Soc., 2012, 134, 17714–17721; (c) S. A. Snyder, D. S. Treitler,
A. P. Brucks and W. Sattler, J. Am. Chem. Soc., 2011, 133, 15898–15901.
Scheme 4 Proof-of-principle direct double cyclisation of (6S*,7R*)-[H
6
]-8
7 For a review see: A. Murai, in Comprehensive Natural Products Chemistry,
ed. D. H. R. Barton, O. Meth-Cohn and K. Nakinishi, Elsevier, Oxford,
into (ꢀ)-[H
6
]-3 via IBIAERO reaction and subsequent bromoetherification of
the remaining unsaturation (cf., Scheme 2).
1
999, vol. 1, pp. 303–324 and references cited therein.
E. Kurosawa, A. Fukuzawa and T. Irie, Tetrahedron Lett., 1972, 13,
121–2124.
8
9
2
(a) Lactoperoxidase (LPO) mediated cyclisation of 7a into 1b (char-
acterized as 1a after acetylation; 0.73% yield): A. Fukuzawa, M. Aye and
A. Murai, Chem. Lett., 1990, 1579–1580(b) LPO mediated cyclisation of
In conclusion, we have demonstrated the proof-of-principle
direct cyclisation of a linear unsaturated C15-precursor into a
C -dibrominated bicyclic medium-ring ether relevant to Laurencia
7
b into 2 (3%): A. Fukuzawa, Y. Takasugi, A. Murai, M. Nakamura and
15
M. Tamura, Tetrahedron Lett., 1992, 33, 2017–2018(c) Bromoperoxidase
(BPO) mediated cyclisation of 7a into 1b (0.015%) and 7b into 2 (‘trace’
amount): A. Fukuzawa, M. Aye, Y. Takasugi, M. Nakamura, M. Tamura
and A. Murai, Chem. Lett., 1994, 2307–2310.
species – where hexahydrolaureoxanyne (ꢀ)-[H ]-3 has an identical
6
bicyclic medium ring ether framework to laureoxanyne 3 – by two
successive bromination events in the same pot. These studies are
also consistent with epoxide (6S,7R)-8 acting as the biogenetic
1
0 K. J. Bonney and D. C. Braddock, J. Org. Chem., 2012, 77, 9574–9584
and references cited therein.
11 For an IBIAERO reaction with capture of the oxonium ion with an
added external nucleophile, see: K. J. Bonney, D. C. Braddock,
A. J. P. White and M. Yaqoob, J. Org. Chem., 2011, 76, 97–104 and
references cited therein.
10
precursor for bromocyclisation to bicyclic medium-ring ethers of
Laurencia species via IBIAERO reactions followed by subsequent
bromoetherification events.
1
2 (a) BPO mediated cyclisation of 1b into 3 (3%): A. Fukuzawa, M. Aye,
M. Nakamura, M. Tamura and A. Murai, Tetrahedron Lett., 1990, 31,
We thank the Dinu Patriciu Foundation for funding (to D.-T. S.).
4895–4898. See ref. 9b for LPO mediated conversion of 1b into
laureatin 5 (0.3%). See ref. 9c for BPO mediated conversion of 1b
Notes and references
2
2
into laureoxanyne 3 (0.8%), and [1- H]-2 into [1- H]-5 (laureatin)
2
‡
We speculate that the truncated C12 epoxide suffers from an intra-
(0.07%) and [1- H]-6 (isolaureatin) (0.05%)(b) For a chemical con-
2
2
molecular hydrogen bond from the alcohol functional group reducing
its nucleophilicity.
version of [1- H]-2 into [1- H]-4 (12%) see: J. Ishihara, Y. Shimada,
N. Kanoh, Y. Takasugi, A. Fukuzawa and A. Murai, Tetrahedron,
1997, 53, 8371–8382.
§
25% of a bis-epoxide was also observed.
¶
Attempted epoxidation of 14 with mCPBA was unselective for the 13 (a) For the formation of the bromoallene of laurallene 4 from
Z-olefins.
(E)-prelaureatin (24%) see: M. T. Crimmins and E. A. Tabet, J. Am.
Chem. Soc., 2000, 122, 5473–5476; for the formation of the tetra-
hydrofuran ring of (ꢁ)-isoprelaurefucin from a pre-existing oxepene
(92%) see: (b) H. Lee, H. Kim, T. Yoon, B. Kim, S. Kim, H.-D. Kim
and D. Kim, J. Org. Chem., 2005, 70, 8723–8729; the actual chemical
conversion of the prelaureatin skeleton into laureatin and/or iso-
laureatin bicyclics has proved challenging: (c) H. Kim, H. Lee,
D. Lee, S. Kim and D. Kim, J. Am. Chem. Soc., 2007, 129, 2269–2274;
(d) M. Sugimoto, T. Suzuki, H. Hagiwara and T. Hoshi, Tetrahedron
Lett., 2007, 48, 1109–1112.
1
13
1
1
8
H- C and H- H NMR correlation spectroscopy were used to distin-
guish between epoxides (6S*,7R*)-[H ]-8 and 15.†
* In an experiment with 1 equivalent of NBS in water, (ꢀ)-[H
isolated in 1.8% yield after extensive chromatography.
† The ‘polar’ components were expected to contain regioisomeric bromo-
6
*
6
]-3 was
†
hydrins and dibromohydrins by reference to our earlier work (ref. 10) and
were not further characterised.
‡‡ The medium-ring bicyclic structure of [H
6
]-3 is also supported by a
and H as previously
characteristic NOESY cross-peak between H
reported (as an nOe) for 3 (ref. 12a).†
7
9
14 (a) Hexahydrolaureoxanyne ([H
[H ]-5): T. Irie, M. Izawa and E. Kurosawa, Tetrahedron Lett., 1968,
2091–2096(c) hexahydroisolaureatin ([H ]-6): T. Irie, M. Izawa and
6
]-3): ref. 12a; (b) hexahydrolaureatin
(
6
1
(a) T. Irie, M. Suzuki and T. Masamune, Tetrahedron Lett., 1965, 16,
6
1
1
091–1099; (b) T. Irie, M. Suzuki and T. Masumune, Tetrahedron,
968, 24, 4193–4205.
E. Kurosawa, Tetrahedron Lett., 1968, 2735–2738; (d) hexahydroiso-
prelaurefucin: M. Suzuki, K. Kurata, T. Suzuki and E. Kurosawa,
Bull. Chem. Soc. Jpn., 1986, 59, 2953–2955.
2
For comprehensive reviews see: (a) B.-G. Wang, J. B. Gloer, N.-Y. Ji
and J.-C. Zhao, Chem. Rev., 2013, 113, 3632–3685; (b) J. W. Blunt, 15 (a) O. Loreau, A. Maret, D. Poullain, J. M. Chardigny, J. L. S ´e b ´e dio,
B. R. Copp, R. A. Keyzers, M. H. G. Munro and M. R. Prinsep, Nat.
Prod. Rep., 2014, 31, 160–258 and earlier reviews in this series.
For a comprehensive review of the synthesis of medium-ring ethers
from Laurencia sp., see: K. Fujiwara, Top. Heterocycl. Chem., 2006, 5,
B. Beaufr `e re and J. P. No ¨e l, Chem. Phys. Lipids, 2000, 106, 65–78; see
also: (b) W. G. Young, L. Richards and J. Azorlosa, J. Am. Chem. Soc.,
1939, 61, 3070–3074; (c) F. P. Coss ´ı o, I. Ganboa and C. Palomo,
Tetrahedron Lett., 1985, 26, 3041–3044; (d) L. M. Smith, R. G. Smith,
T. M. Loehr, G. D. Daves Jr., G. E. Daterman and R. H. Wohleb, J. Org.
Chem., 1978, 43, 2361–2366; (e) B. A n˜ orbe, V. S. Martin, J. M. Palaz ´o n
and J. M. Trujillo, Tetrahedron Lett., 1986, 27, 4991–4994.
3
4
9
7–148. See also ref. 2a.
For recent leading syntheses of C15 Laurencia metabolites see: (a) G. Kim,
T.-i. Sohn, D. Kim and R. S. Paton, Angew. Chem., 2014, 126, 276–280;
(
b) C. Recsei, B. Chan and C. S. P. McErlean, J. Org. Chem., 2014, 79, 16 N. P. Villalva-Servin, A. Laurent and A. G. Fallis, Can. J. Chem., 2004,
80–887; (c) J. Rodr ´ı guez-L ´o pez, N. Ortega, V. S. Mart ´ı n and T. Mart ´ı n,
82, 227–239.
Chem. Commun., 2014, 50, 3685–3688; (d) M. T. Holmes and 17 C. Oger, L. Balas, T. Durand and J.-M. Galano, Chem. Rev., 2013, 113,
R. Britton, Chem. – Eur. J., 2013, 19, 12649–12652; (e) D. J. 1313–1350.
8
Shepherd, P. A. Broadwith, B. S. Dyson, R. S. Paton and J. W. 18 R. Murray and P. Singh, Org. Synth., 1997, 74, 91.
Burton, Chem. – Eur. J., 2013, 19, 12644–12648; ( f ) B. S. Dyson, 19 DMDO epoxidations of cis/trans-dialkylalkene pairs have been reported
J. W. Burton, T.-i. Sohn, B. Kim, H. Bae and D. Kim, J. Am. Chem.
Soc., 2012, 134, 11781–11790; (g) M. J. Kim, T.-i. Sohn, D. Kim and
to have a ca. 10-fold greater reactivity for the former: A. L. Baumstark
and P. C. Vasquez, J. Org. Chem., 1988, 53, 3437–3439.
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